The primary goal of this project is to characterize the ocular zonule biochemically, ultrastructurally and immunologically, to provide tools for investigating diseases of this basic unit in the elastic tissue system. The glycoprotein composing the zonular fibers will be isolated and characterized in bovine and human eyes, to better define zonular microfibrillar protein and determine how many proteins are present in the microfibril structure. NH2-terminals will be sequenced where possible and tests carried out to determine whether lysine-derived crosslinks are involved in binding zonular fibers together. Polyclonal and monoclonal antibodies made to the purified proteins will be used on tissues for investigating abnormalities of the zonule and the ocular elastic tissues. These diseases result in zonular breakage and dislocation of the lens, but are frequently associated with disorders of ocular growth, especially myopia, and so have a broader significance. The dermal elastic system will also be studied in these diseases, as well as in the pseudoexfoliative syndrome, an important cause of glaucoma in the elderly, to determine whether changes in the elastic microfibrillar system are generalized, and if so to characterize the defects. The structural organization of the zonular fibril and its beaded and filamentous components will be studied by rotary shadowing and by immunoelectron microscopy using zonular and matrix antibodies. The cells involved in zonular fibrillogenesis will be investigated in calf eyes by immunoelectron microscopy and in situ hybridization, using a cDNA probe for a new zonule-related protein. Evidence will be sought for zonular receptors on the ciliary and lens epithelial cell surfaces which might be involved in guiding zonular fibril growth. Adhesion proteins mediating zonular-basement membrane attachments will also be investigated immunologically.
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