title: CERKL gene knockout disturbs photoreceptor outer segment phagocytosis and causes rod-cone dystrophy in zebrafish.
abstract: In humans, CERKL mutations cause widespread retinal degeneration: early dysfunction and loss of rod and cone photoreceptors in the outer retina and, progressively, death of cells in the inner retina. Despite intensive efforts, the function of CERKL remains obscure and studies in animal models have failed to clarify the disease mechanism of CERKL mutations. To address this gap in knowledge, we have generated a stable CERKL knockout zebrafish model by TALEN technology and a 7bp deletion in CERKL cDNA that caused the premature termination of CERKL. These CERKL-/- animals showed progressive degeneration of photoreceptor outer segments (OSs) and increased apoptosis of retinal cells, including those in the outer and inner retinal layers. Additionally, we confirmed by immunofluorescence and western-blot that rod degeneration in CERKL-/- zebrafish occurred earlier and was more significant than that in cone cells. Accumulation of shed OSs in the interphotoreceptor matrix was observed by transmission election microscopy (TEM). This suggested that CERKL may regulate the phagocytosis of OSs by the retinal pigment epithelium (RPE). We further found that the phagocytosis-associated protein MERTK was significantly reduced in CERKL-/- zebrafish. Additionally, in ARPE-19 cell lines, knockdown of CERKL also decreased the mRNA and protein level of MERTK, as well as the ox-POS phagocytosis. We conclude that CERKL deficiency in zebrafish may cause rod-cone dystrophy, but not cone-rod dystrophy, while interfering with the phagocytosis function of RPE associated with down-regulation of the expression of MERTK.
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Yu
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Chang
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Life Sciences, Glasgow Caledonian University, Glasgow G4?0BA, UK.
authors.forename: Lincoln
authors.initials: L
authors.lastname: Biswas
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Xuebin
authors.initials: X
authors.lastname: Hu
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Life Sciences, Glasgow Caledonian University, Glasgow G4?0BA, UK.
authors.forename: James
authors.initials: J
authors.lastname: Reilly
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Xiliang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Yuwen
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Zhaojing
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Han
authors.affiliation: Department of Pathology & Lab Medicine, University of Cincinnati Medical Center, Cincinnati, OH 45267, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yu Liu
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.affiliation: Department of Life Sciences, Glasgow Caledonian University, Glasgow G4?0BA, UK.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Shu
authors.affiliation: Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA.
authors.forename: Fulton
authors.initials: F
authors.lastname: Wong
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P.R. China.
authors.forename: Mugen
authors.initials: M
authors.lastname: Liu
mesh_terms: D000818:Animals; D002460:Cell Line; D015536:Down-Regulation; D055786:Gene Knockout Techniques / Q000379:methods; D006801:Humans; D009154:Mutation; D010587:Phagocytosis / Q000235:genetics; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism*; D010786:Photoreceptor Cells; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D012160:Retina / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism; D012162:Retinal Degeneration / Q000235:genetics; D055213:Retinal Pigment Epithelium / Q000378:metabolism; D012174:Retinitis Pigmentosa / Q000378:metabolism; D015027:Zebrafish / Q000235:genetics; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D029961:Zebrafish Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C585195:Cerkl protein, zebrafish; D020794:Receptor Protein-Tyrosine Kinases