Leucine-rich repeat region of decorin binds to filamin-A

Decorin is a member of the family of small leucine-rich proteoglycans found in the extracellular matrix and has an important role in promoting fiber formation and in controlling cell proliferation. Here, we have investigated whether the leucine-rich repeat (LRR) region of decorin interacts with proteins from human lung fibroblasts by using a yeast two-hybrid assay. We report that the LRR region of decorin interacts with the cytoskeletal protein, filamin-A (ABP-280), a peripheral cytoplasmic protein. This interaction is dependent on the 288 carboxyl-terminal amino acids of filamin-A, which correspond to repeats 22-24 of its conserved beta-sheet structure. We also show that the recombinant LRR region of decorin binds to filamin-A in vitro, and that the deglycosylated core protein of decorin coprecipitates with filamin-A, whereas intact decorin does not. Together, these results suggest that proteins containing the LRR motif that interact with filamin-A may be present in the cytoplasm or at the plasma membrane.