Purification of gelatin-specific neutral protease from human skin by conventional and high-performance liquid chromatography

Protein tyrosine phosphorylation in signalling pathways leading to the activation of gelatinase A: activation of gelatinase A by treatment with the protein tyrosine phosphatase inhibitor sodium orthovanadate

Fibroblasts in monolayer culture secrete gelatinase A (MMP2; 72 kDa type IV collagenase) only in its proenzyme form. Unlike other secreted matrix metalloproteinases, progelatinase A is refractory to activation by serine proteinases. Disparate agents, including monensin, cytochalasin D, and concanavalin A, have been found to mediate the activation of gelatinase A zymogen secreted by fibroblast monolayers. Our finding that monensin-mediated activation can be reversed by the protein tyrosine kinase inhibitor genistein (Li et al., Experimental Cell Research 232 (1997) 332) prompted us to investigate the effect of the specific inhibitor of protein tyrosine phosphatases, sodium orthovanadate, on progelatinase A activation. Treatment of fibroblast monolayers with orthovanadate also results in the secretion of activated gelatinase A. This activation is dose- and time-dependent, requires protein synthesis, and is associated with cell membranes. Vanadate-mediated activation does not occur in the presence of herbimycin A, a protein tyrosine kinase inhibitor. As with progelatinase activation mediated by monensin, concanavalin A, and cytochalasin D, orthovanadate treatment results in increased synthesis of the membrane proteinase MT1-MMP, that can catalyze the activation of progelatinase A. Protein tyrosine kinase inhibitors are able to prevent the increase of MT1-MMP mRNA, as shown by Northern blot and RT-PCR. In addition, orthovanadate potentiates the effects of monensin and concanavalin A. While treatment with monensin or concanavalin A result only in an increase of the putative activator MT1-MMP, orthovanadate also reduces the production of the specific inhibitor TIMP-2. These experiments implicate protein tyrosine phosphorylation in the signal transduction pathways which lead to the activation of progelatinase A.

Activation of gelatinase A (72-kDa type IV collagenase) induced by monensin in normal human fibroblasts

In monolayer culture, fibroblasts secrete all matrix metalloproteinases, including gelatinase A (72-kDa type IV collagenase), as inactive zymogens. Whereas limited proteolysis by plasmin or other matrix metalloproteinases (MMPs) can accomplish the extracellular activation of other proenzymes in this family, gelatinase A proenzyme is uniquely refractory to cleavage by such proteinases. Previously it has been shown that fibroblasts cultured in the presumably more physiologic culture milieu of a type I collagen lattice can be induced to secrete active gelatinase A. In monolayer culture, however, the plant lectin concanavalin A will induce gelatinase A activation. Here we show that in monolayer culture activation of gelatinase A by normal fibroblasts is also induced by the sodium ionophore monensin. The monensin response is dose-dependent, time-dependent, requires protein synthesis, and is specific to gelatinase A among the secreted matrix metalloproteinases. The activator appears to be associated with cell membranes and may be membrane-type matrix metalloproteinase 1(MT-MMP1). Both mRNA and immunodetectable protein of MT-MMP1 are increased with monensin treatment while message for the protein inhibitor of gelatinase A, TIMP-2, is unchanged. The monensin-induced signal transduction pathway leading to gelatinase activation in monolayer culture appears to be different from the integrin-mediated pathway operative in the collagen lattice system. The tyrosine kinase inhibitor genistein blocks monensin activation of gelatinase A in monolayer culture. In contrast, genistein has no effect on proenzyme activation in the collagen lattice. Likewise, the cyclooxygenase inhibitor indomethacin abrogates the monensin effect in monolayer culture and can be reversed by addition of exogenous prostaglandin E2 (PGE2). Neither indomethacin nor PGE2 affects activation of gelatinase A in the collagen lattice.

Intracellular activation of gelatinase A (72-kDa type IV collagenase) by normal fibroblasts

Normal fibroblasts cultured as monolayers secrete matrix metalloproteinases (MMP), including gelatinase A (72-kDa type IV collagenase) as inactive zymogens. Previously we found that normal fibroblasts cultured in a type I collagen lattice (dermal equivalent) secrete active gelatinase A. Here we show that the activation of progelatinase A occurs within the cell and that the activator copurifies with Golgi membranes. Cell extracts of fibroblasts cultured in collagen lattices contain active 62-kDa gelatinase A at least 4-6 h before active enzyme is detected in the culture medium. Pulse-chase experiments confirm these results. The activator is membrane-bound and localizes to the Golgi-enriched fraction. Highly purified plasma membranes from lattice cultures are unable to convert gelatinase A from the zymogen to its active form. The activator may be a metalloproteinase because EDTA prevents activation of exogenous proenzyme by membrane fractions. Membrane-type MMP1, the enzyme thought to be responsible for activation of gelatinase A on the plasma membrane of tumor cells, shows no significant change in either mRNA or protein levels during lattice culture. Intracellular levels of gelatinase A mRNA and protein increase during the culture period, and tissue inhibitor of metalloproteinases concentration does not change. Because of the greater availability of tissue inhibitor of metalloproteinases-free proenzyme as a substrate for the activator, it is possible that membrane-type MMP1 is the activating enzyme. In that case, malignant transformation may involve a change in the localization of the activator to the plasma membrane.

Separation of proteases: old and new approaches

All methods of protein separations can be applied to proteases. Some emphasis is put in this review on a powerful technique specific to proteases purification: cyclic peptide antibiotics may be seen as general affinity ligands for proteases. Also, some examples of affinity chromatography of proteases on ligands with narrower specificity are given. The special interest of hydrophobic interaction chromatography for proteases purification is discussed. The merits of immobilized dye chromatography for proteases purification and the interest in empirically screening many immobilized dyes, as well as several eluents are discussed.

Degradation of the COL1 domain of type XIV collagen by 92-kDa gelatinase

Type XIV collagen is a newly described member of the fibril-associated collagens with interrupted triple helices (FACITs). Expression of this collagen has been localized to various embryonic tissues, suggesting that it has a functional role in development. All FACITs thus far described (types IX, XII, XIV, and XVI) contain a highly homologous carboxyl-terminal triple helical domain designated COL1. We have studied the capacity of various matrix metalloproteinases (interstitial collagenase, stromelysin, matrilysin, and 92-kDa gelatinase) to degrade the COL1 domain of collagen XIV. We found that only 92-kDa gelatinase cleaves COL1. Furthermore, digestion of whole native collagen XIV by the 92-kDa gelatinase indicates that this enzyme specifically attacks the carboxyl-terminal triple helix-containing region of the molecule. COL1 is cleaved by 92-kDa gelatinase at 30 degrees C, a full 5-6 degrees C below the melting temperature (Tm) of this domain; native collagen XIV is also degraded at 30 degrees C. In comparison to interstitial collagenase degradation of its physiologic native type I collagen substrate, the 92-kDa enzyme cleaved COL1 (XIV) with comparable catalytic efficacy. Interestingly, following thermal denaturation of the COL1 fragment, its susceptibility to 92-kDa gelatinase increases, but only to a degree that leaves it several orders of magnitude less sensitive to degradation than denatured collagens I and III. These data indicate that native COL1 and collagen XIV are readily and specifically cleaved by 92-kDa gelatinase. They also suggest a role for 92-kDa gelatinase activity in the structural tissue remodeling of the developing embryo.

Application of N-carboxyalkyl peptides to the inhibition and affinity purification of the porcine matrix metalloproteinases collagenase, gelatinase, and stromelysin

Several N-carboxyalkyl peptides were synthesized and tested as inhibitors of pig synovial collagenase, 72-kDa gelatinase and stromelysin (matrix metalloproteinases MMP-1, MMP-2, and MMP-3). The most potent of the series, CH3CH2CH2(R,S)CH(COOH)-NH-Leu-Phe-Ala-NH2, competitively inhibited cleavage of dinitrophenyl-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2 at the Gly-Leu bond by MMP-1 and MMP-2 (KI = 30 and 40 microM, respectively). A similar inhibitory potency was found for MMP-1 with soluble Type I collagen and MMP-3 with substance P as substrate. The inhibitor was coupled to EAH-Sepharose 4B through a C-terminal amide. In the presence of 2 M NaCl at pH 7.2, this matrix bound MMP-1, MMP-2, and MMP-3 from concentrated culture medium of pig synovial membranes. The enzymes coeluted at pH 4.1 and subsequently were resolved by chromatography on DEAE-Sephacel and heparin-Sepharose. Purified MMP-1 catalyzed the o-phenanthroline-sensitive cleavage of collagen into TCA and TCB fragments as well as slower hydrolysis of the alpha 2 chain. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of MMP-1 indicated a predominant polypeptide of approximately 44 kDa and minor species of approximately 24 and 21 kDa. The 44-kDa species and one of the smaller polypeptides reacted with an antiserum to residues 195-207 of human fibroblast MMP-1, indicating that porcine MMP-1 contains a similar sequence and that the smaller components were probably derived from MMP-1. Neither MMP-2 nor MMP-3 reacted with this antiserum. Purified porcine MMP-2 degraded gelatin but not collagen and exhibited an apparent Mr of approximately 71 kDa. Additional smaller polypeptides were present, one of which may correspond to tissue inhibitor of metalloproteinases. MMP-3 showed doublets of approximately 47/46 and 26/25 kDa and cleaved substance P at the Gly6-Phe7 bond. This procedure provides a rapid means of obtaining all three MMPs from one source in approximately 15% yield each.

Potential proteolytic activity of human plasma fibronectin: fibronectin gelatinase

Human plasma fibronectin contains a latent proteinase that after activation cleaves gelatin and fibronectin. The autoactivation propensity of the two purified cathepsin D-produced fragments of fibronectin (190 and 120 kDa) was compared. Both polypeptides were spontaneously activated in the presence of Ca2+. This activation was inhibited by EDTA. The active gelatinase was isolated from the autodigest of the 190-kDa fragment. Among various protein substrates, including laminin and native type I and IV collagens, the purified enzyme degraded only gelatin and fibronectin. We have named this proteinase FN-gelatinase. FN-gelatinase is inhibited by phenylmethanesulfonyl fluoride and also by pepstatin A like retroviral aspartic proteinases. The amino-acid composition of the purified enzyme (35 kDa) was compared with the entire fibronectin sequence using the computer programme FIT. The optimal fit indicated that the 35-kDa fragment corresponds to the stretch # 1043-1404. This sequence contains a 93-residue segment (# 1140-1233) analogous to retroviral aspartic proteinases, comprising the sequence DTG of their putative active site.

Combined lectin-affinity and metal-interaction chromatography for the separation of glycophorins by high-performance liquid chromatography

Human erythrocyte sialoglycoproteins, or glycophorins, were chromatographed by lectin-affinity and metal-interaction chromatography on high-performance liquid chromatographic columns. Glycophorins A, B and C were separated from other proteins and from glycophorin E by using a column containing wheat germ agglutinin, immobilized on a microparticulate silica support. The glycophorins were adsorbed on the lectin column from a mobile phase containing 0.25 M sodium chloride and recovered by stepwise desorption with 0.2 M N-acetylglucosamine solution. Glycophorins A, B and C were separated into the individual components on a silica-bound iminodiacetic acid stationary phase in the copper(II) chelate form. The separation of the glycophorins by metal-interaction chromatography was accomplished by decreasing salt gradient elution. Retention times and resolution of the individual glycophorins were sensitive to the initial sodium chloride concentration and the pH of the eluent. Addition of methanol to the eluent increased the resolution. The effects of linear, decreasing gradients of pH and methanol in 25 mM phosphate buffer on the resolution of glycophorins were also investigated. In both types of chromatography the mobile phases contained 0.05% (w/v) sodium dodecyl sulfate. With octylglycoside or CHAPS in the eluent glycophorins A and C could not be eluted. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was used to analyze all the chromatographic results.

Eriochrome black T inhibition of human skin collagenase, but not gelatinase, using both protein and synthetic substrates

The intracellular degradation of interstitial collagen is accomplished by two neutral metalloproteases, collagenase and gelatinase. Both enzymes are inhibited by metal chelating agents, by certain sulfhydryl reagents, and by similar protein inhibitors. Here, we demonstrate that the dye eriochrome black T (EBT) appears to be unique in its capacity to inhibit collagenase but not gelatinase. Using native reconstituted helical collagen in gel form at 37 degrees C, half-maximal inhibition of collagenase activity by EBT occurs at approximately 45 microM. EBT more effectively inhibits the breakdown of native collagen in solution, with a KI of approximately 8 microM. Using a newly-developed spectrophotometric substrate, AcProLeuGly-S-LeuLeuGly-OC2H5, a KI of 1.4 microM was calculated for EBT on collagenase. Although this same thiopeptolide serves as a substrate for gelatinase with kinetics similar to those of collagenase, no inhibition by EBT was observed. EBT also did not inhibit the gelatinase-mediated breakdown of the natural substrate, gelatin. The data suggest that EBT may have significant potential for allowing the differentiation in biological fluids of two metalloproteases with similar cleavage site specificities.

Cleavage site specificity of vertebrate collagenases

A series of synthetic peptide substrates for vertebrate collagenase having the structure Ac-Pro-Leu-Gly-X-Leu-Gly-OC2H5, where X is Leu, Ile, Val, Phe and Ala, have been prepared. Collagenolytic enzymes from various sources cleave these substrates with differing relative rate patterns. This series of peptides should be valuable for characterization of collagenases.