The Involvement of p53, p63 and p73 in Retinal Ganglion Cell Death After Axonal, Ischemic and Elevated Intraocular Pressure Injury

Abstract

Purpose: : p53, p63 and p73 are members of the p53 gene family involved in development, differentiation and cell response to stress. This study was undertaken to determine their possible involvement in retinal ganglion cell death after experimental injury. We studied the expression of p53, p63 and p73 mRNA in normal adult rat retina after optic nerve transection (ONT), selective ligature of ophthalmic vessels (SLOV) and acute increase in intraocular pressure (IIOP).

Methods: : Tissue samples of rat retina were collected 3, 7 and 14 days after ONT and IIOP, and 24h, 7 and 14 days after SLOV. Total RNA was extracted using Trizol, and cDNA was synthesized. The expression of target genes was evaluated with quantitative real-time PCR with SYBR Green assay. Normal, untreated rat retina samples were used as controls and the relative mRNA expression levels were calculated.

Results: : p53, p63 and p73 mRNA was detected in normal adult rat retina. After ONT the relative level of p53 was increased 1.5-fold at day 7 and p63 mRNA at day 3. p73 mRNA level was increased in all time points, 2-fold at days 3 and 7 and 1.5-fold at day 14. After SLOV the relative level of p53 mRNA showed 2.5-fold increase at 3 and 7 d and returned to normal by day 14. p63 expression increased 1.5-fold at day 3 and returned back to normal by day 7. p73 mRNA expression was increased at all time points. IIOP caused a transient decrease in p53 mRNA level at 24h whereas the relative level of both p63 and p73 mRNA was found to increase after IIOP.

Conclusions: : p63 and p73 expression can be detected from normal adult rat retina. The alterations in the relative mRNA levels of p53, p63 and p73 suggest that these genes are involved in retinal ganglion cell death after ONT, SLOV and IIOP.

Keywords: apoptosis/cell death • ganglion cells • retina: proximal (bipolar, amacrine, and ganglion cells)