Processing and assembly of fibrillin-1

Fibrillins are extracellular matrix proteins of ˜350 kD. They have a complex multidomain structure and are the major components of microfibrillar structures in both elastic and nonelastic tissues (Sakai et al. 1986; Kielty & Shuttleworth 1995). Mutations in the FBN-1 gene cause Marfan Syndrome, which is a heritable connective tissue disease with an incidence of 1:5000 (Lee et al. 1991). Marfan Syndrome is associated with shortened life expectancy due to aortic dissection, as well as range of skeletal and ocular abnormalities (Maslen et al. 1991). The disease may be due to reduced levels of fibrillin-rich microfibrils and/or the presence of structurally or functionally abnormal microfibrils. The mechanism of fibrillin assembly into microfibrils is poorly understood, largely due to the large size and complexity of the protein, and this in turn has hindered a full understanding of the mechanism of the disease. To facilitate study of the secretion and assembly of fibrillin-1 (Fib-1), a minigene construct has been assembled containing the N-and C-terminus and 2 blocks of cysteine rich repeats (exons 1–15 and exons 50–65). This cDNA has been linked at the C-terminus to a green fluorescent protein (GFP) tag in order to visualize the fibrillin minigene construct as it is translocated through the cell and secreted into the extracellular matrix.