The central position of the lens in the optic path as well as accommodation, rely on the zonule of Zinn, an acellular fibrous structure, which has fibrillin-1 as a major component. Ectopia lentis, dislocation of the lens, is a major manifestation of the Marfan syndrome (MFS), a common genetic disorder caused by dominantly inherited FBN1 mutations, of Weill-Marchesani syndrome (caused by FBN1, ADAMTS10 and ADAMTS17 mutations), and isolated ectopia lentis (caused by ADAMTSL4 or FBN1 mutations). These genetic findings strongly suggest a functional link between these ADAMTS (A distintegrin-like and metalloprotease with thrombospondin type-1 repeat) superfamily molecules and fibrillin-1, about which little is known. The hypothesis underlying the proposal is that ADAMTSL4, ADAMTS10 and ADAMTS17 are esential for microfibril assembly in the zonule of Zinn as this structure organizes and bridges the ciliary body and lens. In this proposal, focusing on ADAMTS17 and ADAMTSL4, we will undertake intermolecular interaction analysis using surface plasmon resonance to investigate their individual intermolecular interactions of with fibrillin-1. We will investigate them functionally during fibrillin microfibril formation by cultured cells, and determine whether ADAMTSL4, fibrillin-1 or ADAMTS10 are ADAMTS17 substrates. We will investigate a model in which ADAMTS17, ADAMTSL4 and ADAMTS10 are postulated to work cooperatively to facilitate assembly of the zonule, and investigate the spatial and temporal relationships of the expression of these genes during zonule development. This experimental strategy will reveal the biochemical and functional relationships of ADAMTSL4 and ADAMTS17 with fibrillin-1 and ADAMTS10. It will provide a mechanistic understanding of zonule formation and the cause of ectopia lentis. There is currently no specific treatment for ectopia lentis. The fundamental knowledge obtained through this work may allow design of novel therapeutic approaches for ectopia lentis by identifying the critical factors and mechanisms that mediate zonule assembly and stability.
The outcomes of the proposed work will result in an improved understanding of zonule formation and ectopia lentis mechanisms. The zonule is important because it centers the ocular lens in the path of light, and transmits ciliary muscle contraction to enable accommodation. Ectopia lentis occurs in 60% of patients with the Marfan syndrome, a common genetic disorder affecting the tissue microfibrils, which constitute the zonule. There is currently no specific treatment for ectopia lentis or for regeneration of the zonule. The fundamental knowledge obtained through this work may allow design of novel therapeutic approaches for ectopia lentis by identifying the critical factors and mechanisms that mediate zonule assembly.
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