Characterization of primary cilia in mouse retina during retinal development

Abstract

Purpose : Primary cilia are hair-like organelles that extend from the apical surface of most mammalian cells. Defects in primary cilia in the eye cause ciliopathies, including renal disease, cerebral anomalies and retinitis pigmentosa. Currently, it is well-known that the connecting cilium in rod and cone photoreceptors contribute to phototransduction. However, the role of cilia in non-photoreceptors in the retina remains unknown. The purpose of this study is to describe the distribution of primary cilia in other layers of retina in mouse and human during development.

Methods : In this study, eyes were collected from the different developmental stages in Centrin2-GFP::Arl13b-mCherry transgenic mice, wildtype CD1 mice and C57BL/6J mice to study the distribution of primary cilia in vivo. Retinal sections were stained using Pax6, Sox9, and Chx10 antibodies to determine the fraction of ciliated cells that express these markers. In addition, wildtype CD1 and C57BL/6J mice eyes were used for whole mount of retinal pigment epithelium (RPE) and stained with ZO-1 and Arl13b. Whole mounts of RPE of normal human and AMD patient tissue were performed using a modified iDISCO protocol.

Results : In mouse RPE, primary cilia assembly and disassembly were found to be dynamically regulated during development. In neural retina, we found cilia initially localized in the inner neuroblastic layer at P0 age. By P7, ciliated cells were noted in the outer part of the INL and limited to the inner side of the INL of adult retinas. Further analysis identified most ciliated cells in neuronal retina as Pax6-positive (amacrine marker) at adult age. In human eyes, primary cilia were detected in adult wholemount RPE. Shorter primary cilia of the RPE were found in AMD patient tissue as compared with normal human (n=50, p value<0.05, student t-test).

Conclusions : We showed a novel distribution of primary cilia in non-photoreceptor cells in the retina and RPE in human and mice. These findings highlight possible roles primary cilia could play in retinal development and diseases.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.