title: Haploinsufficiency of RCBTB1 is associated with Coats disease and familial exudative vitreoretinopathy.
abstract: Familial exudative vitreoretinopathy (FEVR) belongs to a group of genetically and clinically heterogeneous disorders in retinal vascular development. To date, in approximately 50% of patients with FEVR, pathogenic mutations have been detected in FZD4, LRP5, TSPAN12, NDP and ZNF408. In this study, we identified two heterozygous frameshift mutations in RCBTB1 from three Taiwanese cases through exome sequencing. In patient-derived lymphoblastoid cell lines (LCLs), the protein level of RCBTB1 is approximately half that of unaffected control LCLs, which is indicative of a haploinsufficiency mechanism. By employing transient transfection and reporter assays for the transcriptional activity of β-catenin, we demonstrated that RCBTB1 participates in the Norrin/FZD4 signaling pathway and that knockdown of RCBTB1 by shRNA significantly reduced nuclear accumulation of β-catenin under Norrin and Wnt3a treatments. Furthermore, transgenic fli1:EGFP zebrafish with rcbtb1 knockdown exhibited anomalies in intersegmental and intraocular vessels. These results strongly support that reduced RCBTB1 expression may lead to defects in angiogenesis through the Norrin-dependent Wnt pathway, and that RCBTB1 is a putative genetic cause of vitreoretinopathies.
authors.affiliation: Department of Life Sciences and Institute of Genome Sciences.
authors.forename: Jeng-Hung
authors.initials: JH
authors.lastname: Wu
authors.affiliation: Department of Ophthalmology, Cheng-Hsin General Hospital, Taipei, 11220, Taiwan, ROC.
authors.forename: Jorn-Hon
authors.initials: JH
authors.lastname: Liu
authors.affiliation: Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei 11221, Taiwan, ROC, Department of Ophthalmology.
authors.forename: Yu-Chieh
authors.initials: YC
authors.lastname: Ko
authors.affiliation: Department of Life Sciences and Institute of Genome Sciences.
authors.forename: Chi-Tang
authors.initials: CT
authors.lastname: Wang
authors.affiliation: Department of Ophthalmology.
authors.forename: Yu-Chien
authors.initials: YC
authors.lastname: Chung
authors.affiliation: Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli 35053, Taiwan, ROC.
authors.forename: Kuo-Chang
authors.initials: KC
authors.lastname: Chu
authors.affiliation: Genome Research Center.
authors.forename: Tze-Tze
authors.initials: TT
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, Cheng-Hsin General Hospital, Taipei, 11220, Taiwan, ROC.
authors.forename: Hsiao-Ming
authors.initials: HM
authors.lastname: Chao
authors.affiliation: Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli 35053, Taiwan, ROC mychung@ym.edu.tw sjchen@vghtpe.gov.tw yjjiang@nhri.org.tw.
authors.forename: Yun-Jin
authors.initials: YJ
authors.lastname: Jiang
authors.affiliation: Department of Ophthalmology, mychung@ym.edu.tw sjchen@vghtpe.gov.tw yjjiang@nhri.org.tw.
authors.forename: Shih-Jen
authors.initials: SJ
authors.lastname: Chen
authors.affiliation: Department of Life Sciences and Institute of Genome Sciences, Department of Medical Research, Taipei Veterans General Hospital, Taipei, 11217, Taiwan, ROC and mychung@ym.edu.tw sjchen@vghtpe.gov.tw yjjiang@nhri.org.tw.
authors.forename: Ming-Yi
authors.initials: MY
authors.lastname: Chung
mesh_terms: D002460:Cell Line; D059472:Exome; D015785:Eye Diseases, Hereditary; D005136:Eye Proteins / Q000378:metabolism; D000080345:Familial Exudative Vitreoretinopathies; D005260:Female; D016368:Frameshift Mutation; D020022:Genetic Predisposition to Disease; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics* / Q000378:metabolism; D057895:Haploinsufficiency; D006801:Humans; D008297:Male; D018919:Neovascularization, Physiologic; D009419:Nerve Tissue Proteins / Q000378:metabolism; D012164:Retinal Diseases / Q000235:genetics*; D058456:Retinal Telangiectasis / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000379:methods*; D013624:Taiwan; D060449:Wnt Signaling Pathway
chemical_list: D005136:Eye Proteins; D020662:Guanine Nucleotide Exchange Factors; C081848:NDP protein, human; D009419:Nerve Tissue Proteins; C482643:RCBTB1 protein, human