Abstract
Purpose: :
Current diagnostic modalities in glaucoma are based on assessment of intraocular pressure (IOP) and visual fields. Glaucoma symptoms often correlate poorly with IOP. This has led to increased interest in serum biomarkers as a potential diagnostic tool. Our group has previously shown that C6orf129 (a hitherto uncharacterized protein) is present at elevated levels in the serum of Pseudoexfoliation Glaucoma patients. The objective of this study was to further investigate the role of this autoantibody in glaucoma.
Methods: :
Rat retinal ganglion (RGC-5) cells were treated with Hydrogen Peroxide (200 µM, 400 µM, or 600 µM) or Calcium Ionophore (A23187) (2µM or 5µM) for 24 hours. mRNA expression of C6orf129, and two key markers of apoptosis (APAF-1 and Caspase 3), were assayed by RT-PCR using gene-specific primers and SyBr-green labeling. Post-treatment cell viability/toxicity was evaluated using crystal violet cell viability assay.
Results: :
Expression of C6orf129 is significantly up-regulated in RGC5 cells following a 24 hour exposure to glaucoma-like stimuli (p=0.03 5µM A23187 treatment, p=0.07 200µM H2O2 treatment) at non-toxic levels as assessed by crystal violet staining (>85% cell viability at all treatment concentrations). In addition, we found a concomitant increase in the key markers of apoptosis (APAF-1; p=0.03 200µM H2O2 treatment) (Caspase-3; p<0.01 200µM H2O2 treatment, p=0.027 2µM A23187, and p=0.047 5µM A23187).
Conclusions: :
Treatment of RGC5 cells with glaucoma-like stimuli increases expression of C6orf129; this is in parallel to markers of apoptosis. These findings suggest a potential relationship between C6orf129 and apoptosis in RGC-5 cells using glaucoma-related stimuli. Further work will include characterization of C6orf129 and exploration of the relationship between these autoantibodies and other forms of glaucoma (Ocular Hypertension/Low Tension Glaucoma/Primary Open Angle Glaucoma).
Keywords: proteomics • ganglion cells • autoimmune disease