Homogeneous, Sulfated Oligosaccharides from Glycosaminoglycans Activate Promatrilysin (proMMP‐7) Largely by Co‐localization

Abstract

Human matrix metalloproteinase‐7 (MMP‐7 or matrilysin) and glycosaminolycans (GAGs) are two important players in extracellular matrix (ECM), participating in innate immunity, aging and cancer. MMP‐7 is over‐expressed in tumor cells and secreted into the ECM as a proenzyme (proMMP‐7). It has been found that MMP‐7 forms complexes with glycoproteins CD44 and heparin‐binding EGF via GAG carbohydrate chains. Recent in vitro studies showed that some GAGs regulate MMP‐7 activities by accelerating proMMP‐7 autolytic cleavage of the pro‐domain (Ra et al., 2009, JBC). We have found recombinant proMMP‐7 to be activated by homogeneous oligosaccharides from heparin in a saccharide length‐dependent manner. 6‐mer, 8‐mer, and 12‐mer heparin oligosaccharides accelerate proMMP‐7 activation at a similar rate while 16‐mer and 20‐mer oligosaccharides accelerate proMMP‐7 activation several‐fold more dramatically. ProMMP‐7 free or bound to the 6‐mer appear to be monomeric by atomic force microscopy. By contrast, proMMP‐7 and the 20‐mer formed large, elongated assemblies. Interface mapping by NMR spectroscopy suggests GAG binding sites in the catalytic and pro domains and potential modes of binding. Our results suggest GAGs regulate proMMP‐7 activation by drawing these protease molecules together. Supported by NIH grant R01GM57289.