Matrix metalloproteinases degrade insulin-like growth factor-binding protein-3 in dermal fibroblast cultures.

摘要: Insulin-like growth factor binding protein-3 (IG-FBP-3) is degraded by a Zn(2+)-dependent protease(s) produced human dermal fibroblasts in vitro (Fowlkes, J. (1994) Endocrine 2, 63-68). Initial studies using IG-FBP-3-substrate zymography identified several IGFBP-3-degrading proteases with M(r) 52,000-72,000, which were inhibitable EDTA and shifted to lower species after treatment of conditioned medium an organomercurial, suggesting that they might represent one or more the matrix metalloproteinases (MMPs). Immunoblotting demonstrated presence proMMP-1 (52 55 kDa), proMMP-3 (58 60 proMMP-2 (72 kDa) whose molecular masses corresponded identically those proteases. Degradation recombinant (rh) IGFBP-3 media was blocked (> 80% inhibition) tissue inhibitor metallo-proteinases-1, specific all MMPs, while removal MMPs -1, -2, -3 from sequential immunoaffinity gelatin-Sepharose chromatography resulted complete loss proteinase activity. Furthermore, MMP-1, MMP-3, lesser extent MMP-2 rhIGFBP-3 vitro. Sequence analysis cleavage sites each cleaved within mid-region protein, domain little no homology other five cloned IGFBPs. These suggest beyond their previously described functions as extracellular degrading enzymes, may also exert effects on cellular proliferation via degradation IGFBP-3, thus enhancing IGF bioavailability.