Reversion‐inducing cysteine‐rich protein with Kazal motifs and MT1‐MMP promote the formation of robust fibrillin fibers

Fibrillins (FBNs) form mesh‐like structures of microfibrils in various elastic tissues. RECK and FBN1 are co‐expressed in many human tissues, suggesting a functional relationship. We found that dermal FBN1 fibers show atypical morphology in mice with reduced RECK expression (RECK‐Hypo mice). Dermal FBN1 fibers in mice‐lacking membrane‐type 1‐matrix metalloproteinase (MT1‐MMP) show a similar atypical morphology, despite the current notion that MT1‐MMP (a membrane‐bound protease) and RECK (a membrane‐bound protease inhibitor) have opposing functions. Our experiments using dermal fibroblasts indicated that RECK promotes pro‐MT1‐MMP activation, increases cell‐associated gelatinase/collagenase activity, and decreases diffusible gelatinase/collagenase activity, while MT1‐MMP stabilizes RECK in these cells. Experiments using purified proteins indicate that RECK and its binding partner ADAMTS10 keep the proteolytic activity of MT1‐MMP within a certain range. These findings suggest that RECK, ADAMTS10, and MT1‐MMP cooperate to support the formation of robust FBN1 fibers.