Abstract
Purpose :
Genetic biomarkers are critical for the early detection of neurodegenerative eye diseases, serving to predict the severity of the disease and its response to treatment. Due to the complexity of neurodegenerative diseases, such as glaucoma, different biomarkers are needed to better study and understand the pathophysiology of these diseases. In this study, two large microarray datasets were used to explore potential biomarkers that would predict the loss of retina ganglion cells.
Methods :
Two microarray datasets were used in this project: 1) Data sets derived from 55 different strains of BXD mice and 2) Data sets from DBA/2J and C57BL/6J mice at the age of 3, 12, and 17 months. Retinas from crushed eyes (n=5) and control eyes (n=5) from three-month-odl BL6 mice were used for RT-PCR verification one month after crush. Pooled retinas from DBA/2J and BL6 mice at 3 months (n=8), 12 months (n=8), and 17 months (n=8) were prepared for RT-PCR analysis. Globes of DBA/2J and BL6 mice were fixed in paraformaldehyde and sectioned for immunofluorescence staining with antibodies against potential RGC markers. Two-tailed Student’s t-test was used for statistical analysis.
Results :
The expression levels of four candidate genes – sncg, kcnd2, pvalb, and cyfip2 – were found to have a strong correlation with the loss of RGCs based on two microarray datasets. RT-PCR analysis showed that the relative expression levels of sncg and pvalb in crushed eye were significantly lower than those of the control eyes (p < 0.05). Similarly, gene microarray analyses, confirmed by RT-PCR, showed a progressive reduction in sncg and pvalb expression in retinas of the DBA/2J glaucomatous mouse compared to their age-matched C57BL/6J control. Furthermore, immunofluorescence microscopy results revealed that in the young and adult mouse retina, sncg is preferentially expressed in RGC somas while pvalb is mainly expressed in RGC dendrites.
Conclusions :
According to the microarray analysis, sncg, kcnd2, pvalb, and cyfip2 are potential RGC markers. RT-PCR results further showed that sncg and pvalb expression levels decreased with the degeneration of RGCs in two different mouse models – the glaucomatous DBA/2J mice and mice that sustained optic nerve crush injury. Additionally, immunofluorescence results demonstrated that sncg and pvalb were specifically expressed in RGCs. In conclusion, the results from this study showed that sncg and pvalb are specific and reliable RGC markers.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.