Dynamic BMP Gene Expression Regulation in Chick RPE During Recovery from Lens-Induced Defocus and Form-Deprivation

Abstract

Purpose : This study investigated the differential gene expression of BMPs in chick retinal pigment epithelium (RPE) during recovery from lens-induced defocus and form-deprivation treatments.

Methods : 14-day old White-Leghorn chicks wore monocular +10 or -10 D lenses or diffusers for 2 or 48 h. The lenses and diffusers were then removed and eyes allowed to recover for 0, 15 min, 2, 24, 48, or 96 h, after which RPE was collected from sacrificed birds. RPE gene expression of BMP2, 4, and 7 was examined using real-time PCR and expression levels in treated and their contralateral control eyes compared.

Results : BMP2 gene expression was up-regulated with the +10 D lens treatment, after both 2 and 48 h. For the 2 h treatment groups, gene expression up-regulation was maintained 15 min into the recovery period, but decreased rapidly thereafter to reach the same level as in contralateral control eyes, with the exception of a short term rebound (up-regulation), 24 h into the recovery period. Meanwhile, for the 48 h treatment groups, BMP2 gene expression decreased gradually from up-regulation at 739 ± 121% to down-regulation at 72 ± 14% over the recovery period. BMP2 gene expression was down-regulated with both -10 D lens and FD treatments, after both 2 and 48 h. BMP2 gene expression continued to be down-regulated 15 min into the recovery period, changing to up-regulation after 2 h of recovery, with the time required for gene expression to return to the same level as in the contralateral control eyes varying with the initial treatment duration. Similar gene expression patterns were observed for BMP4 and BMP7, although the changes were generally smaller.

Conclusions : The dynamic changes in BMP gene expression in chick RPE during recovery from three visual manipulations widely used in studies of eye growth tend to follow similar trends in induced refractive error and/or choroidal thickness changes. Thus this study provides further evidence for the role of the RPE as an important signal relay, and RPE-derived BMPs as critical signaling molecules in eye growth regulation.

This is a 2021 ARVO Annual Meeting abstract.