Abstract
Purpose :
Apolipoprotein A-1 (ApoA1) has recently been identified as an extracellular retinoic acid binding protein secreted by the chick choroid (Summers JA, et al. IOVS 2015; ARVO E-Abstract 2162). The current study was carried out to identify ApoA1 gene expression changes in chick ocular tissues during periods of visually guided eye growth.
Methods :
Form deprivation myopia was induced in two day old white leghorn chicks by application of translucent occluders for 10 days after which time occluders were removed and chicks were allowed to experience unrestricted vision for 0 – 20 days (recovery). Retina, choroids and sclera were isolated from control and treated eyes of chicks and snap frozen in liquid nitrogen. Tissues were homogenized and total RNA was purified, DNAase-treated, and used for the synthesis of cDNA with reverse transcriptase and random hexamers. Steady state ApoA1 mRNA concentrations were quantified from cDNA samples by Taqman real time PCR and normalized using the housekeeping gene, GAPDH. Cycle-threshold data was converted to relative gene expression using CFX-Manager (Bio-rad) and analyzed using paired Student’s t-tests and ANOVA.
Results :
No significant differences in ApoA1 gene expression were detected in retinas and scleras of control and treated chick eyes (p >0.05). In the choroid, ApoA1 mRNA levels were not significantly different between control and treated eyes following 10 days of form deprivation (0 days of recovery) and 1 day of recovery (p>0.05). In contrast, ApoA1 mRNA levels were significantly elevated in choroids following 4 – 20 days of recovery as compared with untreated contralateral control eyes (↑52% - ↑129%, p< 0.05, paired t-test).
Conclusions :
The results of the present study indicate that ApoA1 gene expression is modulated in the choroid during recovery from induced myopia. Considering that ApoA1 can function as a retinoic acid binding protein, our results also suggest that transcriptional control of ApoA1 gene expression in the choroid may provide an additional level of regulation of retinoic acid transport and activity in the eye.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.