Fragile X Mental Retardation Protein expression in the retina is regulated by light

• FMRP mRNA is expressed in the mouse retina.
• FMRP expression is decreased by dark adaptation.
• FMRP is located mostly in the inner retina.

Fragile X Mental Retardation Protein (FMRP) is a RNA-binding protein that modulates protein synthesis at the synapse and its function is regulated by glutamate. The retina is the first structure that participates in vision, and uses glutamate to transduce electromagnetic signals from light to electrochemical signals to neurons. FMRP has been previously detected in the retina, but its localization has not been studied yet. In this work, our objectives were to describe the localization of FMRP in the retina, to determine whether different exposure to dark or light stimulus alters FMRP expression in the retina, and to compare the pattern in two different species, the mouse and chick. We found that both FMRP mRNA and protein are expressed in the retina. By immunohistochemistry analysis we found that both mouse and chick present similar FMRP expression localized mainly in both plexiform layers and the inner retina. It was also observed that FMRP is down-regulated by 24 h dark adaptation compared to its expression in the retina of animals that were exposed to light for 1 h after 24 h in the dark. We conclude that FMRP is likely to participate in retinal physiology, since its expression changes with light exposure. In addition, the expression pattern and regulation by light of FMRP seems well conserved since it was similar in both mouse and chick.

This study describes the location of the Fragile X Mental Retardation Protein in the retina, and shows that its expression is modulated by light or dark adaptation: light adapted retinas present a higher expression of FMRP in relation to dark adapted retinas.Figure optionsDownload high-quality image (388 K)Download as PowerPoint slide