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Title: Functional characterisation of FEVR-related LGR4 missense mutations : implications in Norrin-β-Catenin signalling pathway and angiogenesis
Author: Sanjurjo Soriano, Carla
ISNI:       0000 0004 6350 0846
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2017
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Familial exudative vitreoretinopathy (FEVR) is a genetically heterogeneous blinding disorder characterised by the abnormal development of the retinal vasculature. Genetic studies have led to the identification of eight different genes mutated in FEVR and an additional autosomal dominant locus (EVR3) has been mapped. Recently the EVR3 locus was sequenced using next generation technology leading to the identification of an LGR4 missense variant in the EVR3 family. Subsequent sequencing of LGR4 in a cohort of FEVR patients identified further missense variants. The work in this thesis describes the functional characterisation of LGR4 and its FEVR-related variants to confirm it as a new FEVR disease gene. Zebrafish lgr4 morpholino knockdown followed by mRNA rescue showed that the FEVR-related LGR4 variants were unable to rescue the retinal vasculature defects induced in the fish. Furthermore, the majority of mutations underlying FEVR encode components of the Norrin-ß-Catenin signalling pathway. The TOPflash ß-Catenin reporter assay was used to show that LGR4 potentiates Norrin signalling but the variants located in the binding domain of LGR4 reduce this. Norrin and LGR4 binding assays show that the EVR3 mutation increases the binding affinity between these two proteins hinting at a potential disease mechanism. Finally, an in vitro angiogenesis assay demonstrated that LGR4 plays a role in the development of vascular structures. The identification of LGR4 as a new FEVR gene, and confirmation that LGR4 is a component of the Norrin-ß-Catenin pathway, helps to decipher the molecular mechanisms underlying the normal development of the retinal vasculature and the FEVR disease mechanism. Knowing the gene underlying a disease translates into immediate benefit for patients and families through access to a precise genetic diagnosis and more accurate genetic counselling. Furthermore, this new understanding should contribute to the development of new treatments or therapy, ultimately providing a better quality of life for the patients.
Supervisor: Toomes, Carmel ; Inglehearn, Chris ; Bond, Jacquelyn Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available