The two matrix metalloproteinases, MMP-2 and MMP-9, are known to form various dimer complexes. In the present review, some of these complexes are described along with their biological and pathobiological functions.
Previously we have shown that THP-1 cells synthesize matrix metalloproteinase-9 (MMP-9) where a fraction of the enzyme is strongly linked to a proteoglycan (PG) core protein. In the present work we show that these pro-MMP-9⅐PG heteromers have different biochemical properties compared with the monomeric form of pro-MMP-9. In these heteromers, the fibronectin II-like domain in the catalytic site of the enzyme is hidden, and the fibronectin II-like-mediated binding to gelatin and collagen is prevented. However, a fraction of the pro-MMP-9⅐PG heteromers interacted with gelatin and collagen. This interaction was not through the chondroitin sulfate (CS) part of the PG molecule but, rather, through a region in the PG core protein, a new site induced by the interaction of pro-MMP-9 and the PG core protein, or a non-CS glycosaminoglycan part of the PG molecule. The interaction between pro-MMP-9⅐PG heteromers and gelatin was weaker than the interaction between pro-MMP-9 and gelatin. In contrast, collagen I bound to pro-MMP-9⅐PG heteromers and pro-MMP-9 with approximately the same affinity. Removal of CS chains from the PG part of the heteromers did not affect the binding to gelatin and collagen. Although the identity of the PG core protein is not known, this does not have any impact on the described biochemical properties of the heteromer or its pro-MMP-9 component. It is also shown that a small fraction of the PG, which is not a part of the pro-MMP-9⅐PG heteromer, can bind gelatin. As for the pro-MMP-9⅐PG heteromers, this was independent of the CS chains. The structure that mediates the binding of free PG to gelatin is different from the corresponding structure in the pro-MMP-9⅐PG heteromer, because they were eluted from gelatin-Sepharose columns under totally different conditions. Although only a small amount of pro-MMP-9⅐PG heteromer is formed, the heteromer may have fundamental physiological importance, because only catalytic amounts of the enzyme are required to digest physiological targets.A large number of genetically unrelated proteins are known to contain highly negatively charged glycosaminoglycan (GAG) 2 chains. Such core proteins, substituted with GAG chains, constitute an entity of glycoproteins called proteoglycans (PGs). There are several types of GAG chains, where chondroitin sulfate (CS) and heparin/heparan sulfate (HS) are two major types (1). All GAG chains are unbranched, and they contain a variable number of negatively charged sulfate groups that are important for their function (2). Some PGs are associated with cells, whereas others are secreted and are a part of the extracellular matrix (ECM). Almost all mammalian cells synthesize PGs. Monocytes and macrophages synthesize PGs, which are mainly substituted with CS chains (CSPG) and only a minor proportion of HS (3, 4). In resting monocytes most of the CSPG is not released but sorted to the endocytic pathway and degraded (4). However, when monocytes are stimulated and differentiated to macrophages, both the biosynthesis and the secretion of CSPG are i...
Previously, we have shown that a proportion of the matrix metalloproteinase-9 (MMP-9) synthesized by the macrophage cell line THP-1 binds to a chondroitin sulfate proteoglycan (CSPG) core protein to form a reductionsensitive heteromer. It was also shown that the hemopexin-like (PEX) domain and the fibronectin-like (FnII) module in the enzyme are involved in heteromer formation. In this paper, we show that reduction-sensitive and SDS-stable heteromers may be reconstituted in vitro by mixing proMMP-9 with either serglycin, versican or CSPGs isolated from various monocytic cell lines. In addition, a strong but SDS-soluble proMMP-9ÁCSPG heteromer was formed. The two macromolecules in the SDS-stable reduction-sensitive heteromers were not linked together by disulfide bonds. As for the heteromer isolated from THP-1 cells, in vitro reconstituted SDSstable and SDS-soluble heteromers showed weaker binding to gelatin than the proMMP-9 monomer. Furthermore, gelatin inhibited in vitro reconstitution of the heteromers, showing that the FnII module is involved in the complex formation. Tissue inhibitor of metalloproteinase (TIMP)-1 was not be detected in the proMMP-9ÁCSPG complexes. However, the presence of TIMP-1 inhibited formation of the SDS-soluble heteromer, but not the SDS-stable reduction-sensitive heteromer. This indicates that different regions in the PEX domain are involved formation of these heteromers. Structured digital abstract• proMMP-9 and proMMP-9 bind by comigration in gel electrophoresis (View interaction)• proMMP-9 and proMMP-9 bind by zymography (View interaction)
Inhibitors targeting bacterial enzymes should not interfere with enzymes of the host, and knowledge about structural determinants for selectivity is important for designing inhibitors with a therapeutic potential. We have determined the binding strengths of two hydroxamate compounds, galardin and compound 1b for the bacterial zinc metalloproteases, thermolysin, pseudolysin and auerolysin, known to be bacterial virulence factors, and the two human zinc metalloproteases MMP-9 and MMP-14. The active sites of the bacterial and human enzymes have huge similarities. In addition, we also studied the enzyme-inhibitor interactions by molecular modelling. The obtained Ki values of galardin for MMP-9 and MMP-14 and compound 1b for MMP-9 are approximately ten times lower than previously reported. Compound 1b binds stronger than galardin to both MMP-9 and MMP-14, and docking studies indicated that the diphenyl ether moiety of compound 1b obtains more favourable interactions within the S´1-subpocket than the 4-methylpentanoyl moiety of galardin. Both compounds bind stronger to MMP-9 than to MMP-14, which appears to be due to a larger S´1-subpocket in the former enzyme. Galardin, but not 1b, inhibits the bacterial enzymes, but the galardin Ki values were much larger than for the MMPs. The docking indicates that the S´1-subpockets of the bacterial proteases are too small to accommodate the diphenyl ether moiety of 1b, while the 4-methylpentanoyl moiety of galardin enters the pocket. The present study indicates that the size and shape of the ligand structural moiety entering the S´1-subpocket is an important determinant for selectivity between the studied MMPs and bacterial MPs.
Mold particles from Aspergillus fumigatus, Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum have been linked to respiratory-related diseases. We characterized X-ray-inactivated spores and hyphae fragments from these species by number of particles, morphology, and mycotoxin, β-glucan and protease content/activity. The pro-inflammatory properties of mold particles were examined in human bronchial epithelial cells (BEAS-2B) and THP-1 monocytes and phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1. Spores from P. chrysogenum and S. chartarum contained some hyphae fragments, whereas the other preparations contained either spores or hyphae. Each mold species produced mainly one gelatin-degrading protease that was either of the metallo-or serine type, while one remains unclassified.Mycotoxin levels were generally low. Detectable levels of β-glucans were found mainly in hyphae particle preparations. PMA-differentiated THP-1 macrophages were by far the most sensitive model with effects in the order of 10 ng/cm 2 . Hyphae preparations of A. fumigatus and P. chrysogenum were more potent than respective spore preparations, whereas the opposite seems to be true for A. versicolor and S. chartarum.Hyphae fragments of A. fumigatus, P. chrysogenum, and A. versicolor enhanced the release of metalloprotease (proMMP-9) most markedly. In conclusion, species, growth stage, and characteristics are all important factors for pro-inflammatory potential. K E Y W O R D Sβ-glucans, cytokines, mold particles, morphology, mycotoxins, proteases | BACKGROUNDThere is sufficient evidence from epidemiological studies of associations between indoor dampness/mold and adverse health effects including respiratory symptoms, respiratory infections, and exacerbation of asthma. 1,2 Several kinds of indoor air pollution agents may contribute. Mold has been suggested to be particularly important, as it may not only cause infection and toxic effects, but also trigger allergic and non-allergic inflammatory reactions that may be linked to various respiratory-related diseases. [3][4][5] Quantitative guidelines (thresholds) for acceptable levels of indoor contamination of microorganisms/mold have not been suggested. 1 However, for the work environment where exposure levels can be much higher, a proposal has been made. 6 Species that commonly occur in moist indoor environments into tangled mass of networks known as mycelia. Spores from many species, but not all, are easily aerosolized. Spores from some species, for example, S. chartarum are produced in slimy aggregates which are dispersed by water and may become airborne after secondary dispersion. 6 Furthermore, experimental studies have demonstrated that not only spores but also hyphae fragments can be liberated from fungal cultures. [7][8][9] Recently, an immune-microscopic method for their detection has been described. 10 In addition to direct microscopic quantification, 9 components like ergosterol, 11 polysaccharides such as β(1→3)-glucans 12 and enzymes such as p...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.