Generation and activity of the ternary gelatinase B/TIMP-1/LMW-stromelysin-1 complex

Immunolocalization of Enamelysin (Matrix Metalloproteinase-20) in the Forming Rat Incisor

In the rat model, we used the continuously growing incisor to study the expression pattern of matrix metalloproteinase-20 (MMP-20) during the formation of mineralized dental tissues. Casein zymography analysis of extracts of the forming part of the incisor revealed lysis bands corresponding to both the latent form at 57 kD and the active 46- and 41-kD forms, whereas omission of proteinase inhibitors during protein extraction resulted in a single band at 21 kD. A higher molecular weight form of 78 kD was also stained with MMP-20 and TIMP-2 antibodies in Western blotting, and was therefore believed to correspond to an MMP-20/TIMP-2 complex. Immunohistochemical and immunogold electron microscopic results demonstrated strong MMP-20 staining in the forming outer enamel, which diminished near the dentino-enamel junction, but dentin and predentin were unstained. A strong concentration of MMP-20 was seen in the stratum intermedium (SI), particularly at the earlier stages of enamel development. Our results confirm the presence of MMP-20 protein in ameloblasts and odontoblasts of rat incisor and show it to be localized in the same sites of the forming enamel as amelogenin. Their expression is transient in odontoblasts but persists in ameloblasts, and in both cases the expression of amelogenin preceded that of MMP-20 suggesting a developmentally controlled regulation.

Non-Invasive Biomarkers for Duchenne Muscular Dystrophy and Carrier Detection

Non-invasive biological indicators of the absence/presence or progress of the disease that could be used to support diagnosis and to evaluate the effectiveness of treatment are of utmost importance in Duchenne Muscular Dystrophy (DMD). This neuromuscular disorder affects male children, causing weakness and disability, whereas female relatives are at risk of being carriers of the disease. A biomarker with both high sensitivity and specificity for accurate prediction is preferred. Until now creatine kinase (CK) levels have been used for DMD diagnosis but these fail to assess disease progression. Herein we examined the potential applicability of serum levels of matrix metalloproteinase 9 (MMP-9) and matrix metalloproteinase 2 (MMP-2), tissue inhibitor of metalloproteinases 1 (TIMP-1), myostatin (GDF-8) and follistatin (FSTN) as non-invasive biomarkers to distinguish between DMD steroid naïve patients and healthy controls of similar age and also for carrier detection. Our data suggest that serum levels of MMP-9, GDF-8 and FSTN are useful to discriminate DMD from controls (p < 0.05), to correlate with some neuromuscular assessments for DMD, and also to differentiate between Becker muscular dystrophy (BMD) and Limb-girdle muscular dystrophy (LGMD) patients. In DMD individuals under steroid treatment, GDF-8 levels increased as FSTN levels decreased, resembling the proportions of these proteins in healthy controls and also the baseline ratio of patients without steroids. GDF-8 and FSTN serum levels were also useful for carrier detection (p < 0.05). Longitudinal studies with larger cohorts are necessary to confirm that these molecules correlate with disease progression. The biomarkers presented herein could potentially outperform CK levels for carrier detection and also harbor potential for monitoring disease progression.

Comparison of Salivary TIMP-1 Levels in Periodontally Involved and Healthy Controls and the Response to Nonsurgical Periodontal Therapy

Background. Periodontal disease is a chronic inflammatory condition affecting the supporting structures of the dentition. Periodontal destruction is an outcome of the imbalance between matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases (TIMPs). We wanted to prove the hypothesis that salivary TIPM-1 level will vary in different people. A decrease in TIMP-1 level could make them more susceptible to periodontitis whereas a normal level could prevent increased tissue destruction thereby inhibiting the progression from gingivitis to periodontitis. This could probably pave the way for TIPM-1 to be a specific salivary biomarker and serve as a useful diagnostic and therapeutic tool in periodontitis. Methods. Whole unstimulated saliva of 2 ml was collected from twenty-five periodontally healthy and twenty-seven systemically healthy subjects with periodontitis. Clinical parameters recorded at baseline and reevaluated after four weeks in subjects with periodontitis following nonsurgical periodontal therapy were gingival index (GI), oral hygiene index-Simplified (OHI-S), probing pocket depth, and clinical attachment level (CAL). Salivary TIMP-1 levels in both were analyzed using a commercially available ELISA kit.

PEGylation extends circulation half-life while preserving in vitro and in vivo activity of tissue inhibitor of metalloproteinases-1 (TIMP-1)

Excess proteolytic activity of matrix metalloproteinases (MMPs) contributes to the development of arthritis, cardiovascular diseases and cancer progression, implicating these enzymes as therapeutic targets. While many small molecule inhibitors of MMPs have been developed, clinical uses have been limited, in part by toxicity and off-target effects. Development of the endogenous tissue inhibitors of metalloproteinases (TIMPs) as recombinant biopharmaceuticals represents an alternative therapeutic approach; however, the short plasma half-life of recombinant TIMPs has restricted their potential in this arena. To overcome this limitation, we have modified recombinant human TIMP-1 (rhTIMP-1) by PEGylation on lysine residues. We analyzed a mixture of mono- and di-PEGylated rhTIMP-1 species modified by attachment of 20 kDa mPEG chains (PEG(20K)-TIMP-1), as confirmed by SELDI-TOF mass spectrometry. This preparation retained complete inhibitory activity toward the MMP-3 catalytic domain and partial inhibitory activity toward full length MMP-9. Pharmacokinetic evaluation showed that PEGylation extended the plasma half-life of rhTIMP-1 in mice from 1.1 h to 28 h. In biological assays, PEG(20K)-TIMP-1 inhibited both MMP-dependent cancer cell invasion and tumor cell associated gelatinase activity. Overall these results suggest that PEGylated TIMP-1 exhibits improved potential for development as an anti-cancer recombinant protein therapeutic, and additionally may offer potential for clinical applications in the treatment of other diseases.

Cisplatin and PI3kinase inhibition decrease invasion and migration of human ovarian carcinoma cells and regulate matrix-metalloproteinase expression

Targeting of the PI3K (phosphoinositide3-kinase)/Akt/mTOR pathway in human ovarian cancer cells is a promising novel therapeutic strategy. We investigated the effects of cisplatin and the PI3K inhibitor LY294002 on invasion, migration and the expression of essential matrix metalloproteinases (MMPs) in ovarian cancer cells. SKOV3, OVCAR5 and IGROV1 human ovarian cancer cell lines were treated with cisplatin, LY294002 and a combination of both drugs. Invasion and migration of treated cells was assessed using Matrigel and uncoated PET membrane assays. Expression levels of pro-MMP2, MMP2, TIMP1, TIMP2 and MT1-MMP were determined using Western Blotting. Gel zymography was used to quantitate the functional levels of active MMP2. All three cell lines showed significantly reduced invasion and migration after treatment with cisplatin, LY294002, and the combination of both drugs compared to untreated controls. In SKOV3 cells, cisplatin alone and in combination with LY294002 resulted in a 6.3 and 7.1-fold reduction in the total amount of activated MMP2. TIMP1 expression decreased by 5.0, 6.6 and 28.4-fold with cisplatin, LY294002 and the combination respectively (P < 0.05). In contrast, only cisplatin and the combination of both drugs resulted in a significant, 3.7 and 5.1-fold reduction in the level of TIMP2. Expression levels of MT1-MMP remained unchanged. These observations were corroborated in IGROV1 cell lines that showed similar changes of activated MMP2 and TIMP2 expression, but no significant decrease in TIMP1 levels. Our data suggests that inhibition of ovarian cancer cell motility is mediated via down-regulation of activated MMP2, TIMP1 and TIMP2 expression under these treatment conditions.

Exposure to pro-inflammatory cytokines upregulates MMP-9 synthesis by mesenchymal stem cells-derived osteoprogenitors

An intimate interplay exists between the bone and the immune system, which has been recently termed osteoimmunology. The activity of immune cells affects the intrinsic balance of bone mineralization and resorption carried out by the opposing actions of osteoblasts and osteoclasts. The aim of this study was to determine the possible interaction between inflammatory-induced conditions and matrix metalloproteinases-2,-9 (MMP-2,-9) synthesis and secretion by bone marrow-derived osteoprogenitor cells during advanced stages of osteogenesis. Rat bone marrow-derived mesenchymal stem cells (MSCs) were cultured in the presence of osteogenic supplements in order to direct the cells towards the osteogenic differentiation lineage. At the late stages of osteogenesis, assessed by histochemistry, immunohistochemistry and RT-PCR, cultures were exposed to pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 alpha (IL-1 alpha). Biochemical, histochemical and molecular biology techniques were used to discern the influence of pro-inflammatory cytokines on MMP-2,-9 synthesis and secretion. Results indicated that MMP-9 synthesis and secretion were significantly induced after exposure to the cytokines (TNF-alpha, IL-1 alpha) treatment, while MMP-2 levels remained unchanged. These results indicate that in response to inflammatory processes, osteoblasts, in addition to osteoclasts, can also be involved and contribute to the process of active bone resorption by secretion and activation of MMPs.

A biochemical model of matrix metalloproteinase 9 activation and inhibition

Matrix metalloproteinases (MMPs) are a class of extracellular and membrane-bound proteases involved in an array of physiological processes, including angiogenesis. We present a detailed computational model of MMP9 activation and inhibition. Our model is validated to existing biochemical experimental data. We determine kinetic rate constants for the processes of MMP9 activation by MMP3, MMP10, MMP13, and trypsin; inhibition by the tissue inhibitors of metalloproteinases (TIMPs) 1 and 2; and MMP9 deactivation. This computational approach allows us to investigate discrepancies in our understanding of the interaction of MMP9 with TIMP1. Specifically, we find that inhibition due to a single binding event cannot describe MMP9 inhibition by TIMP1. Temporally accurate biphasic inhibition requires either an additional isomerization step or a second lower affinity isoform of MMP9. We also theoretically characterize the MMP3/TIMP2/pro-MMP9 and MMP3/TIMP1/pro-MMP9 systems. We speculate that these systems differ significantly in their time scales of activation and inhibition such that MMP9 is able to temporarily overshoot its final equilibrium value in the latter. Our numerical simulations suggest that the ability of pro-MMP9 to complex TIMP1 increases this overshoot. In all, our analysis serves as a summary of existing kinetic data for MMP9 and a foundation for future models utilizing MMP9 or other MMPs under physiologically well defined microenvironments.

Tumour invasion and matrix metalloproteinases

Matrix metalloproteinases (MMPs) are proteolytic enzymes which play a major role in tumour invasion. They are mainly produced by host stromal cells in most carcinomas and their expression implies a close co-operation between tumour and stromal cells. Increasing data also demonstrate that, in association with a process of epithelial-to-mesenchymal transition, many MMPs can be expressed by tumour cell themselves. Their most well-known role is the degradation of extra-cellular matrix macromolecules which in turn may regulate tumour invasion in some conditions. This ECM degradation generates some matrikins which are also implicated in tumour invasion and angiogenesis. Moreover, MMPs are also implicated in the degradation of cell adhesion molecules and release and activation of growth factors.

Occurrence of two distinct types of tissue inhibitor of metalloproteinases-2 in teleost fish

We have cloned for the first time two cDNAs encoding distinct types of tissue inhibitor of metalloproteinases-2 (TIMP-2) from teleost fish, Japanese flounder, and designated these types as jfTIMP-2a and jfTIMP-2b. The open reading frames of the jfTIMP-2a and jfTIMP-2b cDNAs are composed of 663 and 657 nucleotides and 221 and 219 amino acids, respectively. Both jfTIMP-2s contain 12 cysteine residues, which might form six disulfide bonds as in other animals' TIMP-2s. The predicted full-length amino acid sequence of jfTIMP-2a has lower identity to jfTIMP-2b (63%) than to those of human (74%) and chicken (73%) TIMP-2s, but higher than to those of other human TIMPs (TIMP-1: 39%, TIMP-3: 43%, TIMP-4: 45%), indicating that jfTIMP-2a is a common TIMP-2, while jfTIMP-2b is unique to Japanese flounder. However, the C-terminal region including the last three disulfide bonds of jfTIMP-2b has higher amino acid identity to those of other animal TIMP-2s than to that of jfTIMP-2a. Reverse-transcribed polymerase chain reaction (RT-PCR) analysis showed the mRNAs of jfTIMP-2a and jfTIMP-2b to be ubiquitously expressed in all tissues examined, but with different expression patterns. These findings suggest that the two distinct jfTIMP-2s might perform different functions in teleost tissues.

Enhanced degradation of proteins of the basal lamina and stroma by matrix metalloproteinases from the salivary glands of Sjögren's syndrome patients: correlation with reduced structural integrity of acini and ducts

OBJECTIVE

To determine the effect of matrix metalloproteinase (MMP) activity from the labial salivary glands (LSGs) of Sjögren's syndrome (SS) patients on proteins of the extracellular matrix (ECM) that form the basal lamina and stroma, and to compare this effect with the structural integrity of acini and ducts as well as the functionality of the LSGs.

METHODS

Gelatinase activity was determined by zymography. The digestion pattern of extracellular matrix (ECM) macromolecules was detected by gel electrophoresis and quantified by densitometry. The structural integrity of acini and ducts was evaluated by light and electron microscopy. Secretory function was evaluated by measuring unstimulated salivary flow and by scintigraphy.

RESULTS

LSG extracts showed increased levels of proteolytic activity toward purified proteins of the basal lamina (laminin and type IV collagen) and stroma (types I and III collagen and fibronectin). Enhanced degradation was most evident for fibronectin, laminin, and type IV collagen. Analysis of the ultrastructure of the acinar and ductal basal lamina revealed abnormalities ranging from disorganization to disappearance of this ECM structure. These changes were paralleled by an important loss of microvilli on the apical surface, as well as decreased unstimulated salivary flow. Interestingly, the results were similar in LSGs from all SS patients, regardless of the proximity of infiltrating mononuclear cell foci.

CONCLUSION

Our observation that the proteolytic action of MMPs toward ECM macromolecules is increased in SS patients provides a rationale for understanding the dramatic changes in the structural organization observed in the basal lamina and apical surface of acini in these patients. The results provide new evidence that acinar and ductal cells from the LSGs of SS patients display a molecular potential, with increased capacity to markedly disorganize their ECM environment and, thus, damage their architecture and functionality.

Extracellular matrix remodelling: the role of matrix metalloproteinases

Matrix metalloproteinases (MMPs) are a growing family of metalloendopeptidases that cleave the protein components of the extracellular matrix and thereby play a central role in tissue remodelling. For many years following their discovery, MMPs were believed to function primarily as regulators of ECM composition and to facilitate cell migration simply by removing barriers such as collagen. It is becoming increasingly clear, however, that MMPs are implicated in the functional regulation of a host of non-ECM molecules that include growth factors and their receptors, cytokines and chemokines, adhesion receptors and cell surface proteoglycans, and a variety of enzymes. MMPs therefore play an important role in the control of cellular interactions with and response to their environment in conditions that promote tissue turnover, be they physiological, such as normal development, or pathological, such as inflammation and cancer. This review summarizes some of the recent discoveries that have shed new light on the role of MMPs in physiology and disease.

Role of matrix metalloproteinase-9 in in vitro invasion of esophageal carcinoma cells

BACKGROUND AND OBJECTIVES

Although some investigators recently suggested that MMP-9 may play a critical role in invasion and metastasis, along with MMP-2, in esophageal carcinoma, there has been no direct evidence that MMPs play a critical role in the actual invasion of esophageal carcinoma cells. Here, we investigated the role of MMPs in the in vitro invasion of esophageal carcinoma cell lines (TE-series).

METHODS

Our methods included in vitro invasion assay, gelatin zymography, and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Four cell lines (but not TE-5) secreted MMP-2 and MMP-9 in the culture medium. Using a quantitative in vitro invasion assay, we found a significant (P = 0.002) correlation between the extent of in vitro invasion and the amount of MMP-9, but not of MMP-2, secreted into the conditioned medium in the four cell lines. In these cell lines, R-94138, a specific MMP-9 inhibitor, inhibited in vitro invasion in a dose-dependent manner. Although TE-5 did not secrete MMP-2 or MMP-9, the cells showed a strong in vitro invasion.

CONCLUSIONS

Our data suggest that most of the esophageal carcinoma cell lines use MMP-9 for in vitro invasion, but others may use proteinase(s) other than MMP-9.

Structural insight into the complex formation of latent matrix metalloproteinase 2 with tissue inhibitor of metalloproteinase 2

Matrix metalloproteinases (MMPs) are a family of multidomain enzymes involved in the physiological degradation of connective tissue, as well as in pathological states such as tumor invasion and arthritis. Apart from transcriptional regulation, MMPs are controlled by proenzyme activation and a class of specific tissue inhibitors of metalloproteinases (TIMPs) that bind to the catalytic site. TIMP-2 is a potent inhibitor of MMPs, but it has also been implicated in a unique cell surface activation mechanism of latent MMP-2/gelatinase A/type IV collagenase (proMMP-2), through its binding to the hemopexin domain of proMMP-2 on the one hand and to a membrane-type MMP activator on the other. The present crystal structure of the human proMMP-2/TIMP-2 complex reveals an interaction between the hemopexin domain of proMMP-2 and the C-terminal domain of TIMP-2, leaving the catalytic site of MMP-2 and the inhibitory site of TIMP-2 distant and spatially isolated. The interfacial contact of these two proteins is characterized by two distinct binding regions composed of alternating hydrophobic and hydrophilic interactions. This unique structure provides information for how specificity for noninhibitory MMP/TIMP complex formation is achieved.

Matrix metalloproteinases in tumor invasion and metastasis

Extensive work on the mechanisms of tumor invasion and metastasis has identified matrix metalloproteinases (MMPs) as key players in the events that underlie tumor dissemination. Studies using natural and synthetic MMP inhibitors, as well as tumor cells transfected with cDNAs encoding the MMPs characterized thus far have provided compelling evidence that MMP activity can induce or enhance tumor survival, invasion and metastasis. Because of the ability of MMPs to degrade extracellular matrix (ECM) proteins, the principal mechanism whereby MMPs promote tumor development has been thought to be the proteolytic breakdown of tissue barriers to invasion and the associated facilitation of circulating tumor cell extravasation. However, recent evidence stemming from the use of novel experimental approaches indicates that MMPs do not play a major role in the process of extravasation itself. Rather, they appear to promote intravasation (the process of penetrating the circulation following invasion of blood vessels) and regulate the relationship between tumor cells and host tissue stroma subsequent to extravasation. In addition, the discoveries that a growing number of proteolytically active MMPs may localize to the cell surface in association with adhesion receptors, and that MMP substrates include latent cytokines and growth factors, provide a new conceptual framework for the mechanisms whereby MMPs influence tumor behavior.

Biochemical characterization of the catalytic domain of membrane-type 4 matrix metalloproteinase

A C-terminal truncated form of membrane-type 4 matrix metalloproteinase (MT4-MMP; MMP 17), lacking the hemopexin-like and transmembrane domain, was expressed in Escherichia coli. The catalytic domain was produced by tryptic activation of the recombinant proenzyme and proved to be catalytically active towards the fluorogenic substrate for matrix metalloproteinases (7-methoxycoumarin-4-yl) acetyl-Pro-Leu-Gly-Leu(3-(2,4-dinitrophenyl)-L-2,3-diaminopro-p ionyl)-Ala-Arg-NH2. In contrast to the other three MT-MMPs (MT1-, MT2-, and MT3-MMP), the catalytic domain of MT4-MMP does not activate progelatinase A, nor does it hydrolyze one of the offered extracellular matrix (ECM) proteins, such as collagen types I, II, III, IV, and V, gelatin, fibronectin, laminin or decorin. TIMP-1, a poor inhibitor of MT1-, MT2- and MT3-MMP, suppresses MT4-MMP activity effectively. The progelatinase A/TIMP-2 complex that usually reacts like TIMP-2 also inhibits MT4-MMP. TIMP-2, a strong inhibitor of other MT-MMPS, inhibits MT4-MMP at low concentrations. With increasing TIMP-2 concentration, however, activity passes through a minimum and then increases until at high TIMP-2 concentration the activity is the same as in the absence of TIMP-2. TIMP-1 or the progelatinase A/TIMP-2 complex do not prevent reactivation of MT4-MMP catalytic domain at high TIMP-2 concentrations.

Activation of progelatinase A and progelatinase A/TIMP-2 complex by membrane type 2-matrix metalloproteinase

C-terminal truncated membrane-type 2 matrix metalloproteinase (MT2-MMP1-269), comprising prodomain and catalytic domain, was expressed as a soluble protein in Escherichia coli. Unlike the corresponding form of MT1-MMP, which can be isolated as a 31 kDa protein, MT2-MMP1-269 proved to be comparatively instable, and already the freshly isolated preparation displayed several proteins in SDS-PAGE representing MT2-MMP1-269 (33 kDa) and four N-truncated forms with N-termini methionine32 (30 kDa), isoleucine37 (30 kDa), leucine84 (24 kDa), and leucine93 (22 kDa), the catalytic domain. After thawing of frozen preparations the 33 and the 30 kDa proforms were no longer detectable in SDS-PAGE, and only the 24 and 22 kDa forms remained. The catalytic domain of MT2-MMP activated progelatinase A as well as the progelatinase A/TMP-2 complex by cleaving the 72 kDa progelatinase A to yield 67 kDa gelatinase A, which is then transformed into 62 kDa gelatinase A. The 62 kDa form is about twice as active as the 67 kDa form towards the synthetic substrate N-(2,4)-dinitrophenyl-Pro-Gln-Gly-Ile-Ala-Gly-Gln-D-Arg. No significant difference in activity was found between free and complexed gelatinase A forms. the activation of the progelatinase A/TIMP-2 complex proceeds in two steps: At first MT2-MMP is inhibited by the progelatinase A/TIMP-2/MT2-MMP, complex, whereby a ternary complex, progelatinase A/TIMP-2/ MT-2MMP is generated. This ternary complex is then activated by excess MT2-MMP. Our results suggest a mechanism for spatially regulated extracellular gelatinase A activity mediated by activation with membrane-type MMPs; Free gelatinase A is released into the extracellular space, while gelatinase A/TIMP-2 bound to MT-MMP remains anchored on the cell surface.