Tissue inhibitor of metalloproteinase-3 differentially binds to components of Bruch's membrane.
BACKGROUND
Sorsby's fundus dystrophy (SFD) is caused by mutations in tissue inhibitor of metalloproteinase (TIMP)-3 and, with the exception of early onset, is similar to age-related macular degeneration. The pathological features of this condition relate to the accumulation of TIMP-3 in Bruch's membrane.


OBJECTIVE
To compare the extracellular membrane-binding characteristics of wild-type and four SFD-mutant TIMP-3s.


METHODS
COS-7 cells were transfected with wild-type, Ser-181, Gly-167, Ser-156 and Tyr-168 SFD-mutant TIMP-3 cDNA. The TIMP-3 proteins subsequently synthesised were harvested, analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, semiquantified by ELISA and used in binding assays on the basis of the retention of the wild-type and SFD-mutant TIMP-3 proteins by components of Bruch's membrane.


RESULTS
SFD-mutant TIMP-3s could not be distinguished from wild-type TIMP-3 by the extents to which they aggregated or adhered to type-I collagen, type-IV collagen, fibronectin, laminin, elastin, chondroitin sulphates A, B and C, and heparin sulphate. Of these macromolecules, the wild-type and SFD-mutant TIMP-3s exhibited greatest affinity for elastin and laminin.


CONCLUSIONS
The similarity in the physical and extracellular membrane-binding characteristics of wild-type and SFD-mutant TIMP-3s indicates that these properties are not responsible for the difference in timing of onset of SFD and age-related macular degeneration.
Majid
M A
MA
Academic Unit of Ophthalmology, University of Bristol, Bristol Eye Hospital, Bristol, UK.
Smith
V A
VA
Matthews
F J
FJ
Newby
A C
AC
Dick
A D
AD
D000818:Animals; D016570:Bruch Membrane / Q000378:metabolism*; D019556:COS Cells; D002522:Chlorocebus aethiops; D003317:Corneal Dystrophies, Hereditary / Q000235:genetics; D004549:Elastin / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D007797:Laminin / Q000378:metabolism; D017354:Point Mutation; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D007797:Laminin; D019717:Tissue Inhibitor of Metalloproteinase-3; D004549:Elastin