Differential gene expression of BMP2 and BMP receptors in chick retina & choroid induced by imposed optical defocus

Abstract

Recent studies have demonstrated the defocus sign-dependent, bidirectional gene expression regulation of bone morphogenetic proteins, BMP2, 4 and 7 in chick RPE. In this study, we examined the effects of imposed positive (+10 D) and negative (−10 D) lenses on the gene expression of these BMPs and BMP receptors (BMPR1A, BMPR1B, BMPR2) in chick retina and choroid after monocular lens treatment for 2 or 48 hours, as indicators of the roles of retinal and choroidal BMPs and receptors in postnatal eye growth regulation. In retina, although all genes were expressed, neither +10 nor −10 D lenses, worn for either 2 or 48 h, significantly altered gene expression. In contrast, treatment-related differential gene expression was detected in the choroid for both BMPs and their receptors, although interestingly, with the +10 D lens, BMP2 was up-regulated by 156.7 ± 19.7 % after 2 h, while BMPR1A was down-regulated to 82.3 ± 12.5 % only after 48 h. With the −10 D lens, only the gene expression of BMPR1B was significantly altered, being up-regulated by 162.3 ± 21.2 % after 48 h. Untreated birds showed no difference in expression between their two eyes, for any of the genes examined. The finding that retinal gene expression for BMP2, 4, 7 and their receptors are not affected by short-term optical defocus contrasts with previous observations of sign-dependent expression changes for the same genes in the RPE. The latter changes were also larger and more consistent in direction than the choroidal gene expression changes reported here. The interrelationship between these various changes and their biological significance for eye growth regulation are yet to be elucidated.

Pathway analysis identifies altered mitochondrial metabolism, neurotransmission, structural pathways and complement cascade in retina/RPE/ choroid in chick model of form-deprivation myopia

“…For example, the gene BMP2 that Zhang, Liu & Wildsoet (2012) reported as mainly localised in the retina of chick, has previously been identified as a potential risk factor for myopia in chick retina/RPE ( McGlinn et al, 2007 ) and in chick RPE ( Zhang, Liu & Wildsoet, 2012 ). In a further cohort by the same lab ( Zhang et al, 2016 ), BMP2 was reported as non-significantly expressed in chick retina. Such contradictory results raise issues about the independence of differential gene signalling by BMP2 suggesting that BMP2 perturbation may be more related to other genes responding to the visual manipulation.…”

BMP‑6 protects retinal pigment epithelial cells from oxidative stress‑induced injury by inhibiting the MAPK signaling pathways

“…We aim to further analyze this in the future. Zhang et al reported that numerous types of BMP receptor (BMPR), including BMPR1A, BMPR1B and BMPR2, were expressed in the retina and choroid (37). Hemojuvelin (HJV) is an iron-regulatory protein and a BMP coreceptor; HJV -/mice have been reported to accumulate excess iron in the retina, and exhibit aberrant vascularization and retinal hemangiomas (38).…”

Dim Light Exposure and Myopia in Children

“… 35 However, the relative contributions of the peripheral and central retina are still debated, and it is unknown if these protective inputs are due to rod versus cone stimulation to the retina or optical consequences. 36 – 41 …”