Knocking out lca5 in zebrafish causes cone-rod dystrophy due to impaired outer segment protein trafficking

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1865

Article

Qu, Zhen¹  Yimer, Tinsae Assefa¹  Xie, Shanglun¹  Wong, Fulton²  Yu, Shanshan¹  Liu, Xiliang¹  Han, Shanshan¹  Ma, Juanjuan¹  Lu, Zhaojing¹  Hu, Xuebin¹  Qin, Yayun¹  Huang, Yuwen¹  Lv, Yuexia¹  Li, Jingzhen¹  Tang, Zhaohui¹  Liu, Fei¹  Liu, Mugen¹ 

[1] Huazhong Univ Sci & Technol, Coll Life Sci & Technol, Key Lab Mol Biophys, Minist Educ, Wuhan 430074, Hubei, Peoples R China

[2] Duke Univ, Sch Med, Dept Ophthalmol, Durham, NC 27710 USA

关键词: LCA5;    CRISPR/Cas9;    Zebrafish;    Photoreceptor degeneration;    Ift88;   

DOI  :  10.1016/j.bbadis.2019.07.009

来源: Elsevier

【 摘 要 】

Leber congenital amaurosis (LCA) is the most serious form of inherited retinal dystrophy that leads to blindness or severe visual impairment within a few months after birth. Approximately 1-2% of the reported cases are caused by mutations in the LCA5 gene. This gene encodes a ciliary protein called LCA5 that is localized to the connecting cilium of photoreceptors. The retinal phenotypes caused by LCA5 mutations and the underlying pathological mechanisms are still not well understood. In this study, we knocked out the lca5 gene in zebrafish using CRISPR/Cas9 technology. An early onset visual defect is detected by the ERG in 7 dpf lca5(-/-) zebrafish. Histological analysis by HE staining and immunofluorescence reveal progressive degeneration of rod and cone photoreceptors, with a pattern that cones are more severely affected than rods. In addition, ultrastructural analysis by transmission electron microscopy shows disordered and broken membrane discs in rods' and cones' outer segments, respectively. In our lca5(-/-) zebrafish, the red-cone opsin and cone a-transducin are selectively mislocalized to the inner segment and synaptic terminal. Moreover, we found that Ift88, a key component of the intraflagellar transport complex, is retained in the outer segments. These data suggest that the intraflagellar transport complex-mediated outer segment protein trafficking might be impaired due to lca5 deletion, which finally leads to a type of retinal degeneration mimicking the phenotype of cone-rod dystrophy in human. Our work provides a novel animal model to study the physiological function of LCA5 and develop potential treatments of LCA.

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