Ablation of EYS in zebrafish causes mislocalisation of outer segment proteins, F-actin disruption and cone-rod dystrophy

Zhaojing Lu,Dinesh C Soares,Daji Luo,Xiliang Liu,Zhaohui Tang,Yayun Qin,Shanshan Han,Chang Li,Mugen Liu,An-Yuan Guo,Fei Liu,Tao Jiang,Shanshan Yu,Meng Gao,Xuebin Hu

doi:10.1038/srep46098

Abstract

Mutations in EYS are associated with autosomal recessive retinitis pigmentosa (arRP) and autosomal recessive cone-rod dystrophy (arCRD) however, the function of EYS and the molecular mechanisms of how these mutations cause retinal degeneration are still unclear. Because EYS is absent in mouse and rat, and the structure of the retina differs substantially between humans and Drosophila, we utilised zebrafish as a model organism to study the function of EYS in the retina. We constructed an EYS-knockout zebrafish-line by TALEN technology which showed visual impairment at an early age, while the histological and immunofluorescence assays indicated the presence of progressive retinal degeneration with a cone predominately affected pattern. These phenotypes recapitulate the clinical manifestations of arCRD patients. Furthermore, the EYS−/− zebrafish also showed mislocalisation of certain outer segment proteins (rhodopsin, opn1lw, opn1sw1, GNB3 and PRPH2), and disruption of actin filaments in photoreceptors. Protein mislocalisation may, therefore, disrupt the function of cones and rods in these zebrafish and cause photoreceptor death. Collectively, these results point to a novel role for EYS in maintaining the morphological structure of F-actin and in protein transport, loss of this function might be the trigger for the resultant cellular events that ultimately lead to photoreceptor death.

Highlights

IntroductionWe constructed an EYS-knockout zebrafish-line by TALEN technology which showed visual impairment at an early age, while the histological and immunofluorescence assays indicated the presence of progressive retinal degeneration with a cone predominately affected pattern
EYS mutations are associated with autosomal recessive retinitis pigmentosa (arRP) and autosomal recessive cone-rod dystrophy (arCRD), both of these retinal diseases lead to photoreceptor death and vision loss
In order to understand the pathological process and molecular mechanism of retinal degeneration caused by EYS mutations for better clinical diagnosis and therapy, we generated an EYS knockout zebrafish-line, identified progressive retinal degeneration in this EYS deficient model and investigated the function of zebrafish EYS in vivo

Summary

Introduction

We constructed an EYS-knockout zebrafish-line by TALEN technology which showed visual impairment at an early age, while the histological and immunofluorescence assays indicated the presence of progressive retinal degeneration with a cone predominately affected pattern. These phenotypes recapitulate the clinical manifestations of arCRD patients. Disrupt the function of cones and rods in these zebrafish and cause photoreceptor death. Mutations in EYS are recognised as a major cause for autosomal recessive retinitis pigmentosa (arRP)[4,5,6,7], accounting for 5–18% arRP patients in different populations[4,8,9], and have been identified in patients with autosomal recessive cone-rod dystrophy (arCRD)[10,11].

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Results

Conclusion