Structural effects of fibulin 5 missense mutations associated with age-related macular degeneration and cutis laxa

Jones, R.P.O., Ridley, C., Jowitt, T.A., Wang, M.C., Howard, M., Bobola, N., Wang, T., Bishop, P.N., Kielty, C.M., Baldock, C., Lotery, A.J. and Trump, D. (2010) Structural effects of fibulin 5 missense mutations associated with age-related macular degeneration and cutis laxa. Investigative Ophthalmology & Visual Science, 51 (5), 2356-2362. (doi:10.1167/iovs.09-4620). (PMID:20007835)

Abstract

PURPOSE: AMD has a complex etiology with environmental and genetic risk factors. Ten fibulin 5 sequence variants have been associated with AMD and two other fibulin 5 mutations cause autosomal-recessive cutis laxa. Fibulin 5 is a 52-kDa calcium-binding epidermal growth factor (cbEGF)-rich extracellular matrix protein that is essential for the formation of elastic tissues. Biophysical techniques were used to detect structural changes in the fibulin 5 mutants and to determine whether changes are predictive of pathogenicity.

METHODS: Native PAGE, nonreduced SDS-PAGE, size-exclusion column multiangle laser light scattering, sedimentation velocity, and circular dichroism (CD) were used to investigate the mobility, hydrodynamic radii, folding, and oligomeric states of the fibulin 5 mutants in the absence and presence of Ca(2+).

RESULTS: CD showed that all mutants are folded, although perturbations to secondary structure contents were detected. Both cutis laxa mutants increased dimerization. Most other mutants slightly increased self-association in the absence of Ca(2+) but this was also demonstrated by G202R, a polymorphism detected in a control individual. The AMD-associated mutant G412E showed lower-than-expected mobility during native-PAGE, the largest hydrodynamic radius for the monomer form and the highest levels of aggregation in both the absence and presence of Ca(2+).

CONCLUSIONS: The results identified structural differences for the disease-causing cutis laxa mutants and for one AMD variant (G412E), suggesting that this may also be pathogenic. Although the other AMD-associated mutants showed no gross structural differences, they cannot be excluded as pathogenic by differences outside the scope of this study-for example, disruption of heterointeractions.

This record has no associated files available for download.

Contributors

Author: A.J. Lotery

Download statistics