Decorin Binds Fibrinogen in a Zn2+-dependent Interaction

Abstract

We have previously shown that decorin, a member of the small leucine-rich proteoglycan family of extracellular matrix proteoglycans/glycoproteins is a Zn(2+) metalloprotein at physiological Zn(2+) concentrations (Yang, V. W-C., LaBrenz, S. R., Rosenberg, L. C., McQuillan, D., and Höök, M. (1999) J. Biol. Chem. 274, 12454-12460). We now report that the decorin proteoglycan binds fibrinogen in the presence of Zn(2+). The fibrinogen-binding site is located in the N-terminal domain of the decorin core protein and a 45-amino acid peptide representing this domain binds to the fibrinogen D fragment with an apparent K(D) of 1.7 x 10(-6) m, as determined from fluorescence polarization data. Furthermore, we show that Zn(2+) promotes the self-association of decorin. The N-terminal domain of the core protein also mediates this activity. The results of solid-phase binding assays and gel filtration chromatography suggest that the N-terminal domain of decorin, when present at low micromolar concentrations, forms an oligomer in a Zn(2+)-dependent manner. Thus, Zn(2+) appears to play a pivotal role in the interactions and biological function of decorin.

Novel Zinc-binding Site in the E2 Domain Regulates Amyloid Precursor-like Protein 1 (APLP1) Oligomerization

“…Consistent with our findings, the crossinteraction of zinc and heparin could implicate the C-terminal part of the E2 domain as a general regulatory site for APLP1 oligomerization, as well as for binding interactions with components of the extracellular matrix. Notably, several extracellular matrix protein interactions in non-neuronal tissues have been shown to be regulated by zinc (50,51). It is possible that locally elevated concentrations of zinc could also facilitate such interactions in the brain by the ability of zinc to modulate extracellular matrix interactions with APP/APLPs.…”

Decorin Antagonizes IGF Receptor I (IGF-IR) Function by Interfering with IGF-IR Activity and Attenuating Downstream Signaling

“…Because decorin is a Zn 2ϩ metalloprotein (56), and this cation promotes the binding of decorin to fibrinogen, collagen, fibronectin (57), and myostatin (58), we performed binding experiments in the absence or presence of increasing concentrations (0 -120 M) of ZnCl 2 . Notably, we found no effect of Zn 2ϩ in modulating the binding of recombinant decorin protein core to either IGF-I or IGF-IR (not shown), indicating that this protein-protein interaction is independent of Zn 2ϩ .…”

Decorin Modulates Fibrin Assembly and Structure

“…To prevent decorin core protein from being generated with galactosaminoglycan polysaccharides, we used CHO-745 cells deficient in xylosyltransferase activity (51). Next, decorin core protein bearing an N-terminal His tag was purified from the cell culture medium on an Ni 2ϩ -chelated chromatographic matrix (49,50). The purity and identity of decorin core protein were verified by SDS-PAGE with Coomassie Brilliant Blue R-250 staining and by Western blotting with rabbit anti-decorin polyclonal antiserum PR2 and alkaline phosphatase-conjugated goat anti-rabbit IgG (Bio-Rad) (50).…”

“…Proteins-Recombinant human decorin core protein was produced using a vaccinia virus-based mammalian cell culture system as described previously (49,50). To prevent decorin core protein from being generated with galactosaminoglycan polysaccharides, we used CHO-745 cells deficient in xylosyltransferase activity (51).…”

“…This corroborates analytical ultracentrifugation results showing that biglycan proteoglycan occurs as a hexamer in the presence of Zn 2ϩ ions while in monomer-dimer equilibrium with EDTA (48). Subsequently, we discovered that Zn 2ϩ ions enable the N-terminal region of decorin core protein to self-associate and specifically recognize the D regions of fibrinogen (49).…”