title: Nitric oxide regulates matrix metalloproteinase-9 activity by guanylyl-cyclase-dependent and -independent pathways.
abstract: Matrix metalloproteinases (MMPs) are of central importance in the proteolytic remodeling of matrix and the generation of biologically active molecules. MMPs are distinguished by a conserved catalytic domain containing a zinc ion, as well as a prodomain that regulates enzyme activation by modulation of a cysteine residue within that domain. Because nitric oxide (NO) and derived reactive nitrogen species target zinc ions and cysteine thiols, we assessed the ability of NO to regulate MMPs. A dose-dependent, biphasic regulatory effect of NO on the activity of MMPs (MMP-9, -1, and -13) secreted from murine macrophages was observed. Low exogenous NO perturbed MMP/tissue inhibitor of metalloproteinase (TIMP)-1 levels by enhancing MMP activity and suppressing the endogenous inhibitor TIMP-1. This was cGMP-dependent, as confirmed by the cGMP analog 8-bromo-cGMP, as well as by the NO-soluble guanylyl cyclase-cGMP signaling inhibitor thrombospondin-1. Exposure of purified latent MMP-9 to exogenous NO demonstrated a concentration-dependent activation and inactivation of the enzyme, which occurred at higher NO flux. These chemical reactions occurred at concentrations similar to that of activated macrophages. Importantly, these results suggest that NO regulation of MMP-9 secreted from macrophages may occur chemically by reactive nitrogen species-mediated protein modification, biologically through soluble guanylyl-cyclase-dependent modulation of the MMP-9/TIMP-1 balance, or proteolytically through regulation of MMP-1 and -13, which can cleave the prodomain of MMP-9. Furthermore, when applied in a wound model, conditioned media exhibiting peak MMP activity increased vascular cell migration that was MMP-9-dependent, suggesting that MMP-9 is a key physiologic mediator of the effects of NO in this model.
authors.affiliation: Radiation Biology Branch and Laboratory of Pathology, National Cancer Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA. ridnourl@mail.nih.gov
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Ridnour
authors.forename: Alisha N
authors.initials: AN
authors.lastname: Windhausen
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Isenberg
authors.forename: Nolan
authors.initials: N
authors.lastname: Yeung
authors.forename: Douglas D
authors.initials: DD
authors.lastname: Thomas
authors.forename: Michael P
authors.initials: MP
authors.lastname: Vitek
authors.forename: David D
authors.initials: DD
authors.lastname: Roberts
authors.forename: David A
authors.initials: DA
authors.lastname: Wink
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D006146:Guanidines / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000378:metabolism*; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009569:Nitric Oxide / Q000494:pharmacology*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors; D026361:Reactive Nitrogen Species / Q000494:pharmacology; D012995:Solubility / Q000187:drug effects; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000037:antagonists & inhibitors
chemical_list: D006146:Guanidines; D008070:Lipopolysaccharides; D026361:Reactive Nitrogen Species; D019715:Tissue Inhibitor of Metalloproteinase-1; D009569:Nitric Oxide; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; D020780:Matrix Metalloproteinase 9; D006162:Guanylate Cyclase; C004479:pimagedine