Structure of the human TIMP-3 gene and its cell cycle-regulated promoter

Tissue Inhibitors of Metalloproteinase 1 (TIMP-1) and 3 (TIMP-3) as New Markers of Acute Kidney Injury After Massive Burns

BACKGROUND Acute kidney injury (AKI) is a common and serious complication after massive burn injury. One of the postulated etiologies is destruction of the extracellular matrix of nephrons, caused by a local imbalance between matrix metalloproteinases (MMPs) and specific inhibitors. The aim of this study was to analyze the dynamics of tissue inhibitors of metalloproteinases (TIMPs) during the first 5 days after massive thermal injury and the relationship with the risk of AKI. MATERIAL AND METHODS Thirty-three adults (22 men, 11 women) with severe burns were enrolled in the study. The values of TIMPs 1 to 4 were measured in blood serum and urine using the multiplex Luminex system. The associations between TIMPs and the risk of AKI were analyzed by using the generalized linear mixed models for repeated measurements. RESULTS Significant changes in serum and urine activities of TIMPs were confirmed, especially during the first 2 days after burn injury. Almost half of patients presented renal problems during the study. Significant differences between values of TIMPs in AKI and non-AKI status were also observed. However, a significant relationship between concentration of TIMPs and risk of AKI was confirmed only for urine TIMP-1 and serum TIMP-3. CONCLUSIONS The evaluation of TIMPs in the early stage after burn injury has potential benefits. The important roles of urine TIMP-1 and serum TIMP-3, as novel markers of the risk of AKI development, were confirmed. Other parameters require further analysis.

Why Does Rehabilitation Not (Always) Work in Osteoarthritis? Does Rehabilitation Need Molecular Biology?

Osteoarthritis (OA) is a common disease among the human population worldwide. OA causes functional impairment, leads to disability and poses serious socioeconomic burden. The rehabilitation offers a function-oriented method to reduce the disability using diverse interventions (kinesiotherapy, physical therapy, occupational therapy, education, and pharmacotherapy). OA as a widespread disease among elderly patients is often treated by rehabilitation specialists and physiotherapists, however the results of rehabilitation are sometimes unsatisfactory. The understanding of molecular mechanisms activated by rehabilitation may enable the development of more effective rehabilitation procedures. Molecular biology methods may prove crucial in rehabilitation as the majority of rehabilitation procedures cannot be estimated in double-blinded placebo-controlled trials commonly used in pharmacotherapy. This article attempts to present and estimate the role of molecular biology in the development of modern rehabilitation. The role of clinicians in adequate molecular biology experimental design is also described.

Endometriosis and Opioid Receptors: Are Opioids a Possible/Promising Treatment for Endometriosis?

Endometriosis (EM), defined as the presence of endometrial-like tissue with surrounding smooth muscle cells outside the uterus, is a disregarded gynecological disease reported to affect 6-10% of women of reproductive age, with 30-50% of them suffering from chronic pelvic pain and infertility. Since the exact pathogenic mechanisms of EM are still unclear, no curative therapy is available. As pain is an important factor in EM, optimal analgesia should be sought, which to date has been treated primarily with non-steroidal anti-inflammatory drugs (NSAIDs), metamizole or, in extreme cases, opioids. Here, we review the pain therapy options, the mechanisms of pain development in EM, the endogenous opioid system and pain, as well as the opioid receptors and EM-associated pain. We also explore the drug abuse and addiction to opioids and the possible use of NOP receptors in terms of analgesia and improved tolerability as a target for EM-associated pain treatment. Emerging evidence has shown a promising functional profile of bifunctional NOP/MOP partial agonists as safe and nonaddictive analgesics. However, until now, the role of NOP receptors in EM has not been investigated. This review offers a thought which still needs further investigation but may provide potential options for relieving EM-associated pain.

Loss of TIMP3 by promoter methylation of Sp1 binding site promotes oral cancer metastasis

The tissue inhibitor of metalloproteinase-3 (TIMP3) is the only member of the TIMP family that binds to the extracellular matrix and suppresses cancer cell growth, angiogenesis, migration, and invasion. However, whether the abnormal expression and promoter methylation of TIMP3 facilitates oral cancer metastasis remain unclear. In this study, the DNA methylation levels of TIMP3 CpG islands were assessed through pyrosequencing. Artificial modulation of TIMP3 was performed to explore the role of TIMP3 in tumor metastasis in vitro and in vivo. Our results showed that the suppression of TIMP3 transcription by DNA methylation involves the inhibition of the binding of the transcription factor Sp1 to the TIMP3 promoter as well as the upregulation of DNMT1 and DNMT3B. Functional analyses revealed that TIMP3 overexpression reduced migration and invasion abilities in oral cancer cells and inhibited lymph node metastasis in vivo. Moreover, TIMP3 regulated epithelial-mesenchymal transition by increasing the expression of the epithelial markers and reducing the expression of the mesenchymal markers. In conclusion, our findings suggested that the suppression of TIMP3 by DNA methylation contributes to oral cancer metastasis.

TIMP-3 mRNA expression levels positively correlates with levels of miR-21 in in situ BC and negatively in PR positive invasive BC

BACKGROUND

Breast carcinomas (BC) belong to a heterogeneous group of malignant diseases. Correct categorization of BC based on molecular biomarkers has a very important role in deciding the proper course of therapy for each patient. It has been already shown that the decrease of TIMP metalloproteinase inhibitor 3 (TIMP-3) together with overexpression of microRNA-21 (miR-21) might be involved in the process of BC invasion. This is the first study that examined relationship among miR-21, TIMP-3 mRNA and TIPM-3 protein levels in BC groups formed according to invasiveness.

METHODS

In this study, we used 46 breast cancer samples. Estrogen and progesterone receptor (ER, PR) protein levels were evaluated by immunohistochemistry (IHC) method. TIMP-3 mRNA expression was examined by two-step real-time quantitative PCR (qRT-PCR). Western blot analysis was performed for 16 samples.

RESULTS

Statistically significant differences in TIMP-3 expression levels between invasive groups were discovered in ER positive (ER+) (p=0.015), Her-2 negative (p=0.026) subgroups, and patients without lymph-node metastasis (p=0.039). Interestingly, significant positive correlation was detected between miR-21 and TIMP-3 mRNA levels (P<0.001, ρ=0.949) in the group of in situ tumors. TIMP-3 mRNA expression levels highly negatively correlated with levels of miR-21 in PR+ invasive BCs (p=0.007, ρ=-0.641). TIMP-3 protein levels negatively correlated with miR-21 levels in pure invasive BCs.

CONCLUSION

These data suggest that signaling pathways involved in formation and progression of BCs in groups formed according to invasiveness might be different. Our findings propose that TIMP-3 mRNA expression levels could be significant prognostic parameter, but within specific BC subtypes.

Nondestructive Techniques to Evaluate the Characteristics and Development of Engineered Cartilage

In this review, methods for evaluating the properties of tissue engineered (TE) cartilage are described. Many of these have been developed for evaluating properties of native and osteoarthritic articular cartilage. However, with the increasing interest in engineering cartilage, specialized methods are needed for nondestructive evaluation of tissue while it is developing and after it is implanted. Such methods are needed, in part, due to the large inter- and intra-donor variability in the performance of the cellular component of the tissue, which remains a barrier to delivering reliable TE cartilage for implantation. Using conventional destructive tests, such variability makes it near-impossible to predict the timing and outcome of the tissue engineering process at the level of a specific piece of engineered tissue and also makes it difficult to assess the impact of changing tissue engineering regimens. While it is clear that the true test of engineered cartilage is its performance after it is implanted, correlation of pre and post implantation properties determined non-destructively in vitro and/or in vivo with performance should lead to predictive methods to improve quality-control and to minimize the chances of implanting inferior tissue.

Relationship of MMP-14 and TIMP-3 expression with macrophage activation and human atherosclerotic plaque vulnerability

Matrix metalloproteinase-14 (MMP-14) promotes vulnerable plaque morphology in mice, whereas tissue inhibitor of metalloproteinases-3 (TIMP-3) overexpression is protective. MMP-14(hi) TIMP-3(lo) rabbit foam cells are more invasive and more prone to apoptosis than MMP-14(lo) TIMP-3(hi) cells. We investigated the implications of these findings for human atherosclerosis. In vitro generated macrophages and foam-cell macrophages, together with atherosclerotic plaques characterised as unstable or stable, were examined for expression of MMP-14, TIMP-3, and inflammatory markers. Proinflammatory stimuli increased MMP-14 and decreased TIMP-3 mRNA and protein expression in human macrophages. However, conversion to foam-cells with oxidized LDL increased MMP-14 and decreased TIMP-3 protein, independently of inflammatory mediators and partly through posttranscriptional mechanisms. Within atherosclerotic plaques, MMP-14 was prominent in foam-cells with either pro- or anti-inflammatory macrophage markers, whereas TIMP-3 was present in less foamy macrophages and colocalised with CD206. MMP-14 positive macrophages were more abundant whereas TIMP-3 positive macrophages were less abundant in plaques histologically designated as rupture prone. We conclude that foam-cells characterised by high MMP-14 and low TIMP-3 expression are prevalent in rupture-prone atherosclerotic plaques, independent of pro- or anti-inflammatory activation. Therefore reducing MMP-14 activity and increasing that of TIMP-3 could be valid therapeutic approaches to reduce plaque rupture and myocardial infarction.

Matrix metalloproteinases in coronary artery disease

Matrix metalloproteinases (MMP) are a family of zinc-containing endoproteinases that degrade extracellular matrix (ECM) components. MMP have important roles in the development, physiology and pathology of cardiovascular system. Metalloproteases also play key roles in adverse cardiovascular remodeling, atherosclerotic plaque formation and plaque instability, vascular smooth muscle cell (SMC) migration and restenosis that lead to coronary artery disease (CAD), and progressive heart failure. The study of MMP in developing animal model cardiovascular systems has been helpful in deciphering numerous pathologic conditions in humans. Increased peripheral blood MMP-2 and MMP-9 in acute coronary syndrome (ACS) may be useful as noninvasive tests for detection of plaque vulnerability. MMP function can be modulated by certain pharmacological drugs that can be exploited for treatment of ACS. CAD is a polygenic disease and hundreds of genes contribute toward its predisposition. A large number of sequence variations in MMP genes have been identified. Case-control association studies have highlighted their potential association with CAD and its clinical manifestations. Although results thus far are inconsistent, meta-analysis has demonstrated that MMP-3 Glu45Lys and MMP-9 1562C/T gene polymorphisms were associated with CAD risk.

Bovine lactoferricin induces TIMP-3 via the ERK1/2-Sp1 axis in human articular chondrocytes

Bovine lactoferricin (LfcinB) is a heparan sulfate-binding peptide with multiple bioactivities. In human articular cartilage, LfcinB antagonizes interleukin-1 β (IL-1β) and fibroblast growth factor 2 (FGF-2) in proteoglycan metabolism, catabolic protease expression, and induction of pro-inflammatory mediators. LfcinB specifically activates ERK1/2, p38 and Akt, but whether these signaling pathways control the expression of LfcinB target genes remained unknown. In this report, we characterized a novel aspect of LfcinB-mediated genetic response in human articular chondrocytes, tissue inhibitor of metalloproteinase 3 (TIMP-3) induction. Inhibition of individual signaling pathways revealed that ERK1/2 functions as the major pathway in TIMP-3 expression, whereas Akt plays a minor role. Further investigation identified Sp1 as a critical transcriptional activator in TIMP-3 regulation, and Sp1 activity is modulated by ERK1/2, not Akt. Comparative quantification indicates that significant downregulation of TIMP-3 occurs in OA chondrocytes, suggesting a beneficial role of LfcinB in OA pathogenesis. Our results collectively provide new insights into the mechanism of action of LfcinB, and support the candidacy of LfcinB as a chondroprotective agent.

P14ARF inhibits human glioblastoma-induced angiogenesis by upregulating the expression of TIMP3

Malignant gliomas are the most common and the most lethal primary brain tumors in adults. Among malignant gliomas, 60%-80% show loss of P14ARF tumor suppressor activity due to somatic alterations of the INK4A/ARF genetic locus. The tumor suppressor activity of P14ARF is in part a result of its ability to prevent the degradation of P53 by binding to and sequestering HDM2. However, the subsequent finding of P14ARF loss in conjunction with TP53 gene loss in some tumors suggests the protein may have other P53-independent tumor suppressor functions. Here, we report what we believe to be a novel tumor suppressor function for P14ARF as an inhibitor of tumor-induced angiogenesis. We found that P14ARF mediates antiangiogenic effects by upregulating expression of tissue inhibitor of metalloproteinase-3 (TIMP3) in a P53-independent fashion. Mechanistically, this regulation occurred at the gene transcription level and was controlled by HDM2-SP1 interplay, where P14ARF relieved a dominant negative interaction of HDM2 with SP1. P14ARF-induced expression of TIMP3 inhibited endothelial cell migration and vessel formation in response to angiogenic stimuli produced by cancer cells. The discovery of this angiogenesis regulatory pathway may provide new insights into P53-independent P14ARF tumor-suppressive mechanisms that have implications for the development of novel therapies directed at tumors and other diseases characterized by vascular pathology.

Down-regulation of tissue inhibitor of metalloproteinase-3 (TIMP-3) expression is necessary for adipocyte differentiation

Matrix metalloproteinase activity is essential for proper extracellular matrix remodeling that takes place during adipose tissue formation. Four tissue inhibitors of matrix metalloproteinases (TIMPs) regulate their activity. However, the role of TIMPs in adipocyte differentiation is poorly understood. We found that the expression of all TIMPs was modified during adipocyte differentiation, but that of TIMP-3 was distinguished by its extreme down-regulation. TIMP-3 expression was closely linked to the differentiation process. Indeed, it remained low during the adipocyte differentiation but increased when cell differentiation was prevented. We identified the transcription factor Sp1 as being responsible for the regulation of TIMP-3 expression during adipocyte differentiation. Overexpression of TIMP-3 reduced adipocyte differentiation, underlining its active role in this process. TIMP-3 overexpression decreased the expression of the early and obligate key inductors of adipogenesis Krüppel-like factor 4 (Klf4), early growth response 2 (Egr2/Krox20), and CAAT/enhancer-binding protein beta (C/EBPbeta). Our results indicate that during preadipocyte differentiation, the Sp1-dependent decrease in TIMP-3 expression is required for the successful implementation of the adipocyte differentiation program.

Tissue inhibitor of metalloproteinase 3 suppresses tumor angiogenesis in matrix metalloproteinase 2-down-regulated lung cancer

Matrix metalloproteinase-2 (MMP-2) expression is often up-regulated in advanced cancers and known to play an important role in tumor angiogenesis. We previously showed that adenoviral-mediated delivery of siRNA for MMP-2 (Ad-MMP-2-Si) inhibited lung cancer growth, angiogenesis, and metastasis. In this study, we investigated the signaling mechanisms involved in Ad-MMP-2-Si-mediated inhibition of angiogenesis. Ad-MMP-2-Si treatment inhibited neovascularization in vivo as determined by mouse dorsal air sac model, and conditioned medium from Ad-MMP-2-Si-infected A549 lung cancer cells (Ad-MMP-2-Si-CM) inhibited endothelial tube formation in vitro. Ad-MMP-2-Si-CM decreased proliferation as determined by Ki-67 immunofluorescence and induced apoptosis in endothelial cells as determined by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) assay. Furthermore, Ad-MMP-2-Si-CM inhibited AKT phosphorylation and induced phosphorylation of extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase in endothelial cells. Overexpression of constitutively active AKT reversed the Ad-MMP-2-Si-CM-mediated inhibition of tube formation and induction of ERK phosphorylation. Conversely, Ad-MMP-2-Si-CM induced tissue inhibitor of metalloproteinase (TIMP) 3 expression, and the interaction of vascular endothelial growth factor 2 and TIMP-3 was determined by coimmunoprecipitation experiments. TIMP-3 induction was mediated by ERK activation. In addition, electrophoretic mobility shift and chromatin immunoprecipitation assays show that Sp1 transcription factor mediated Ad-MMP-2-Si-CM-stimulated increase of TIMP-3. Vasculature destruction was confirmed with colocalization studies with TUNEL and an endothelial marker, CD31, in tumor sections of Ad-MMP-2-Si-treated mice. Our data collectively suggest that MMP-2 inhibition induces endothelial apoptosis in vivo and inhibits endothelial tube formation. These experiments provide the first evidence that inhibition of p-AKT and induction of p-ERK1/2 are crucial events in the induction of TIMP-3-mediated endothelial apoptosis in MMP-2 inhibited lung tumors.

Myocardial Matrix Remodeling and the Matrix Metalloproteinases: Influence on Cardiac Form and Function

It is now becoming apparent that dynamic changes occur within the interstitium that directly contribute to adverse myocardial remodeling following myocardial infarction (MI), with hypertensive heart disease and with intrinsic myocardial disease such as cardiomyopathy. Furthermore, a family of matrix proteases, the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs), has been recognized to play an important role in matrix remodeling in these cardiac disease states. The purpose of this review is fivefold: 1) to examine and redefine the myocardial matrix as a critical and dynamic entity with respect to the remodeling process encountered with MI, hypertension, or cardiomyopathic disease; 2) present the remarkable progress that has been made with respect to MMP/TIMP biology and how it relates to myocardial matrix remodeling; 3) to evaluate critical translational/clinical studies that have provided a cause-effect relationship between alterations in MMP/TIMP regulation and myocardial matrix remodeling; 4) to provide a critical review and analysis of current diagnostic, prognostic, and pharmacological approaches that utilized our basic understanding of MMP/TIMPs in the context of cardiac disease; and 5) most importantly, to dispel the historical belief that the myocardial matrix is a passive structure and supplant this belief that the regulation of matrix protease pathways such as the MMPs and TIMPs will likely yield a new avenue of diagnostic and therapeutic strategies for myocardial remodeling and the progression to heart failure.

Novel functions of TIMPs in cell signaling

Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of matrix metalloproteinases (MMPs) and the balance between MMPs/TIMPs regulates the extracellular matrix (ECM) turnover and remodeling during normal development and pathogenesis. Increasing evidence indicates a much more complex role for TIMPs during tumor progression and angiogenesis, in addition to their regulation of MMP-mediated ECM degradation. In this article, we review both the MMP-dependent and -independent actions of TIMPs for the regulation of cell death, cell proliferation, and angiogenesis, with a particular emphasis on TIMP-1 in the regulation of tetraspanin/integrin-mediated cell survival signal transduction pathways.

TGF-beta-induced expression of tissue inhibitor of metalloproteinases-3 gene in chondrocytes is mediated by extracellular signal-regulated kinase pathway and Sp1 transcription factor

Transforming growth factor (TGF-beta1) is a potent inducer of chondrogenesis and stimulant of cartilage extracellular matrix (ECM) synthesis. Tissue inhibitor of metalloproteinases-3 (TIMP-3) is located in ECM and is the major inhibitor of matrix metalloproteinases (MMPs) and aggrecanase, the principal enzymes implicated in collagen and aggrecan degradation in arthritis. We investigated the role of extracellular-signal-regulated kinase (ERK)-mitogen-activated protein kinases (MAPK) and Sp1 transcription factor in TGF-beta-induced TIMP-3 gene in chondrocytes and chondrosarcoma cells. TGF-beta time-dependently induced a sustained phosphorylation of ERK-MAPKs in primary human or bovine chondrocytes. Inhibitors of this pathway, PD98059 and U0126, downregulated TGF-beta-induced expression of TIMP-3 RNA and protein. Since the ERKs can phosphorylate Sp1, and the promoter of human TIMP-3 gene contains four Sp1-binding sites, we investigated whether Sp1 is a downstream target of this pathway. Mithramycin and WP631, the agents that prevent binding of Sp1 to its consensus site, downregulated TGF-beta-inducible TIMP-3 expression. Indeed, mithramycin blocked TGF-beta-stimulated Sp1 binding activity. Transfection of cytomegalovirus (CMV) promoter-Sp1 plasmid increased TIMP-3 promoter (-940 to +376)-driven luciferase activity. Depletion of Sp1 by transfection of an antisense phosphorothioate oligonucleotide suppressed TGF-beta-induced TIMP-3 protein expression, while its sense homolog had no effect. These results suggest that activation of ERK-MAPK pathway and Sp1 transcription factor play a pivotal role in the induction of TIMP-3 by TGF-beta in chondrocytes.

Transforming growth factor Beta1 induction of tissue inhibitor of metalloproteinases 3 in articular chondrocytes is mediated by reactive oxygen species

Transforming growth factor beta1 (TGF-beta1) stimulates cartilage extracellular matrix synthesis but, in excess, evokes synovial inflammation, hyperplasia, and osteophyte formation in arthritic joints. TGF-beta1 induces tissue inhibitor of metalloproteinases 3 (TIMP-3), an inhibitor of cartilage-damaging matrix metalloproteianases and aggrecanases. We investigated the role of reactive oxygen species (ROS) in TIMP-3 induction by TGF-beta1. In primary human and bovine chondrocytes, ROS scavenger and antioxidant N-acetylcysteine (NAC) inhibited TGF-beta1-induced TIMP-3 mRNA and protein increases. Ebselen and ascorbate also reduced this induction. TGF-beta1 time-dependently induced ROS production that was suppressed by NAC. Hydrogen peroxide, a ROS, induced TIMP-3 RNA. The TIMP-3 increase induced by TGF-beta1 was partly Smad2-dependent. TGF-beta1-stimulated Smad2 phosphorylation was inhibited by NAC. Reduced glutathione and L-cysteine also blocked Smad2 and TIMP-3 induction by TGF-beta1, whereas a nonthiol, N-acetylalanine, did not. Smad2 was not activated by H2O2. Smad2 phosphorylation was independent, and TIMP-3 expression was dependent, on new protein synthesis. TGF-beta-stimulated ERK and JNK phosphorylation was also inhibited by NAC. However, inhibitory actions of NAC were not mediated by ERK activation. Thus, ROS mediate TGF-beta1-induced TIMP-3 gene expression. Blocking TGF-beta1-induced gene expression by modulating cellular redox status with thiols can be potentially beneficial for treating arthritic and other disorders caused by excessive TGF-beta1.

Tissue inhibitor of metalloproteinases-1, -2, and -3 polymorphisms in a white population with intracranial aneurysms

BACKGROUND AND PURPOSE

Remodeling of the extracellular matrix seems to be a crucial event in the pathogenesis of cerebral aneurysms. Matrix metalloproteinases are the most important degrading enzymes in the extracellular matrix. Their activity is controlled predominantly by tissue inhibitors of metalloproteinases (TIMPs). To investigate the possible impact of genetic variants within the genes encoding TIMP-1, -2, and -3, we conducted this case-control study.

METHODS

A study sample was analyzed that comprised 44 patients with intracranial aneurysms and 44, 41, and 40 controls for the analysis of TIMP-1, -2, and -3, respectively. Differences in genotype and allele frequencies of identified polymorphisms were determined. The entire coding regions and parts of the promoter sequences of the TIMP-1, -2, and -3 genes were with using the automated laser fluorescence technique.

RESULTS

Nine polymorphisms were identified, 3 located in TIMP-1 (-19C>T, 261C>T, 372T>C), 4 in TIMP-2 (-621C>T, -596A>C, -261G>A, 303G>A), and 2 in TIMP-3 (249T>C, 261C>T), whereas -621C>T, -596A>C, and -261G>A of the TIMP-2 gene are newly identified polymorphisms. We detected no deviation from Hardy-Weinberg equilibrium in any of the groups. The C allele of the 372T>C polymorphism was more frequently found in female than in male controls (exact nominal P=0.0012). However, this finding could not be validated by analysis of a second sample of 113 controls (exact nominal P=1.0000). There were no differences in genotype and allele frequencies between any of the other groups.

CONCLUSIONS

Our analysis of the entire coding region of 3 TIMPs, which are the main inhibitors of metalloproteinase activity in the extracellular matrix, failed to show an association between genetic polymorphisms and an intracranial aneurysm. These data do not support the hypothesis that genetic variants within these genes have an impact on aneurysm development in the white population.

The matrix metalloproteinase system: changes, regulation, and impact throughout the ovarian and uterine reproductive cycle

The ovary and uterus undergo extensive tissue remodeling throughout each reproductive cycle. This remodeling of the extracellular environment is dependent upon the cyclic hormonal changes associated with each estrous or menstrual cycle. In the ovary, tissue remodeling is requisite for growth and expansion of the follicle, breakdown of the follicular wall during the ovulatory process, transformation of the postovulatory follicle into the corpus luteum, as well as the structural dissolution of the corpus luteum during luteal regression. In the uterus, there is extraordinary turnover of the endometrial connective tissue matrix during each menstrual cycle. This turnover encompasses the complete breakdown and loss of this layer, followed by its subsequent regrowth. With implantation, extensive remodeling of the uterus occurs to support placentation. These dynamic changes in the ovarian and uterine extracellular architecture are regulated, in part, by the matrix metalloproteinase (MMP) system. The MMP system acts to control connective tissue remodeling processes throughout the body and is comprised of both a proteolytic component, the MMPs, and a regulatory component, the associated tissue inhibitors of metalloproteinases. The current review will highlight the key features of the MMPs and tissue inhibitors of metalloproteinases, focus on the changes and regulation of the MMP system that take place throughout the estrous and menstrual cycles, and address the impact of the dynamic tissue remodeling processes on ovarian and uterine physiology.

Myocardial remodelling and matrix metalloproteinases in heart failure: turmoil within the interstitium

The progression of left ventricular (LV) dysfunction is often accompanied by changes in LV geometry and myocardial architecture that can be defined as LV myocardial remodelling. An important event in LV myocardial remodelling is alterations in the extracellular matrix (ECM). A family of zinc-dependent proteases implicated in facilitating myocardial tissue remodelling by degrading components of the ECM are the matrix metalloproteinases (MMPs). The temporal expression of MMPs and the local tissue inhibitors of MMPs (TIMPs) appear to be differentially regulated in several cardiovascular disease states such as myocardial infarction, LV hypertrophy, and dilated cardiomyopathy. Both pharmacological and genetic modulation of myocardial MMP expression has been demonstrated to alter the course of LV myocardial remodelling and LV dysfunction. The induction of MMPs within the myocardium during the heart failure process probably results in liberation of bioactive molecules, proteolytic degradation of ECM structural proteins, and alterations in cell-cell contact and adhesion. Modifying MMP expression and activation may reduce this turmoil within the myocardial interstitium and, in turn, prove to be a useful therapeutic paradigm for heart failure treatment.

Tissue inhibitor of metalloproteinase-3 is a basement membrane-associated protein that is significantly decreased in human colorectal cancer

PURPOSE

The balance between local levels of matrix metalloproteinases and tissue inhibitor of metalloproteinases is believed to play a key role in tumor invasion and metastases. Because tissue inhibitor of metalloproteinase-3 suppresses tumorigenicity and tumor invasion in vitro, the aim of this study was to determine its expression in human colorectal cancer.

METHODS

Thirty-nine human colorectal cancer specimens, three adenomas, and matched normal adjacent mucosa from 39 colorectal cancer patients were analyzed. Tissue inhibitor of metalloproteinase-3 ribonucleic acid and protein expression were analyzed by Northern blot hybridization and Western blot analysis, respectively. The cellular localizations of tissue inhibitor of metalloproteinase-3 ribonucleic acid and protein were determined by in situ hybridization and immunolocalization.

RESULTS

Tissue inhibitor of metalloproteinase-3 ribonucleic acid expression was increased in colorectal cancer compared with paired normal mucosa. In contrast, tissue inhibitor of metalloproteinase-3 protein level was higher in normal mucosa than in the corresponding colorectal cancer. In addition, tissue inhibitor of metalloproteinase-3 protein levels progressively decreased with advancing colorectal cancer stages. Tissue inhibitor of metalloproteinase-3 protein tumor to normal mucosa ratio was 0.74 +/- 0.12, 0.51 +/- 0.18, 0.48 +/- 0.12, and 0.45 +/- 0.2 for Dukes A (n = 8), B (n = 9), C (n = 9), and D (n = 13) stages, respectively. Both tissue inhibitor of metalloproteinase-3 messenger ribonucleic acid and protein were located predominantly within spindle-shaped and round stromal cells. Furthermore, in colonic epithelium, tissue inhibitor of metalloproteinase-3 and type IV collagen protein were similarly concentrated in the basal region.

CONCLUSIONS

These data provide the first detailed description of the cellular expression of tissue inhibitor of metalloproteinase-3 in colorectal cancer and identify it as a basement membrane-associated protein. This is an important observation, because the presence of tissue inhibitor of metalloproteinase-3 protein near the basement membrane supports its role in preventing proteolytic degradation, angiogenesis, and apoptosis.

Hypoxia promotes fibrogenesis in human renal fibroblasts

BACKGROUND

The mechanisms underlying progressive renal fibrosis are unknown, but the common association of fibrosis and microvascular loss suggests that hypoxia per se may be a fibrogenic stimulus.

METHODS

To determine whether human renal fibroblasts (HRFs), the primary matrix-producing cells in the tubulointerstitium, possess oxygen-sensitive responses relevant to fibrogenesis, cells were exposed to 1% O2 in vitro.

RESULTS

Hypoxia simultaneously stimulated extracellular matrix synthesis and suppressed turnover with increased production of collagen alpha1(I) (Coll-I), decreased expression of collagenase, and increased tissue inhibitor of metalloproteinase (TIMP)-1. These effects are time dependent, require new RNA and protein synthesis, and are specific to hypoxia. The changes in Coll-I and TIMP-1 gene expression involve a heme-protein O2 sensor and protein kinase- and tyrosine kinase-mediated signaling. Although hypoxia induced transforming growth factor-beta1 (TGF-beta1), neutralizing anti-TGF-beta1-antibody did not block hypoxia-induced Coll-I and TIMP-1 mRNA expression. Furthermore, hypoxic-cell conditioned-medium had no effect on the expression of these mRNAs in naive fibroblasts, suggesting direct effects on gene transcription. Transient transfections identified a hypoxia response element (HRE) in the TIMP-1 promoter and demonstrated HIF-1-dependent promoter activation by decreased ambient pO2.

CONCLUSIONS

These data suggest that hypoxia co-ordinately up-regulates matrix production and decreases turnover in renal fibroblasts. The results support a role for hypoxia in the pathogenesis of fibrosis and provide evidence for novel, direct hypoxic effects on the expression of genes involved in fibrogenesis.

Synergy of demethylation and histone deacetylase inhibition in the re-expression of genes silenced in cancer

Densely methylated DNA associates with transcriptionally repressive chromatin characterized by the presence of underacetylated histones. Recently, these two epigenetic processes have been dynamically linked. The methyl-CpG-binding protein MeCP2 appears to reside in a complex with histone deacetylase activity. MeCP2 can mediate formation of transcriptionally repressive chromatin on methylated promoter templates in vitro, and this process can be reversed by trichostatin A (TSA), a specific inhibitor of histone deacetylase. Little is known, however, about the relative roles of methylation and histone deacetylase activity in the stable inhibition of transcription on densely methylated endogenous promoters, such as those for silenced alleles of imprinted genes, genes on the female inactive X chromosome and tumour-suppressor genes inactivated in cancer cells. We show here that the hypermethylated genes MLH1, TIMP3 (TIMP3), CDKN2B (INK4B, p15) and CDKN2A (INK4, p16) cannot be transcriptionally reactivated with TSA alone in tumour cells in which we have shown that TSA alone can upregulate the expression of non-methylated genes. Following minimal demethylation and slight gene reactivation in the presence of low dose 5-aza-2'deoxycytidine (5Aza-dC), however, TSA treatment results in robust re-expression of each gene. TSA does not contribute to demethylation of the genes, and none of the treatments alter the chromatin structure associated with the hypermethylated promoters. Thus, although DNA methylation and histone deacetylation appear to act as synergistic layers for the silencing of genes in cancer, dense CpG island methylation is dominant for the stable maintenance of a silent state at these loci.

Differential expression of tissue inhibitors of metalloproteinases in the failing human heart

BACKGROUND

Extracellular matrix turnover is regulated by matrix metalloproteinases (MMPs) and a family of tissue inhibitors of metalloproteinases (TIMPs). Together, these proteins may contribute to myocardial remodeling in congestive heart failure. We hypothesized that the expression of MMPs and TIMPs might be differentially regulated in the failing human heart.

METHODS AND RESULTS

Northern blot analyses were performed with probes to TIMP-1 to -4 and GAPDH with poly A+ mRNA from ventricular tissues of patients with ischemic cardiomyopathy (ICM, n=16) or idiopathic dilated cardiomyopathy (DCM, n=15) and nonfailing control hearts (n=15). TIMP-1 to -4 and MMP-9 proteins were quantified by ELISA and/or Western blot, and the total gelatinolytic activity was studied by gelatin zymography. The results showed that cardiac expression of TIMP-1 and -3 transcripts and proteins was significantly reduced in ICM and DCM. No significant difference was observed in TIMP-2 and -4 transcripts. However, TIMP-4 protein was significantly reduced in ICM myocardium. MMP-9 protein content and total gelatinolytic activity were upregulated in the same samples.

CONCLUSIONS

These studies demonstrated a selective downregulation of TIMPs along with upregulation of MMP-9 and gelatinolytic activity in the failing hearts, alterations that favor matrix degradation and turnover. These findings might be of pathophysiological significance and might suggest new therapeutic targets for limiting the ventricular remodeling and dilatation process characteristic of the failing human heart.

Cloning of the human tissue inhibitor of metalloproteinase-4 gene (TIMP4) and localization of the TIMP4 and Timp4 genes to human chromosome 3p25 and mouse chromosome 6, respectively

We have isolated genomic DNA containing the human tissue inhibitor of metalloproteinases-4 gene (TIMP4) and determined the structure of the exons comprising the gene. Like other members of the TIMP family, the TIMP-4 protein is encoded by five exons. These span 6 kb of genomic DNA, so that TIMP4 is similar in size to Timp1 but considerably smaller than TIMP2 and TIMP3. The exon-intron boundaries of TIMP4 are at locations very similar to those of the other TIMP genes, demonstrating the high degree of conservation of gene structure in this family. The human and mouse TIMP-4 genes map to comparable locations in the respective genomes, localizing to human chromosome 3p25 and mouse chromosome 6.

Interleukin (IL)-6 and its soluble receptor induce TIMP-1 expression in synoviocytes and chondrocytes, and block IL-1-induced collagenolytic activity

To define the potential role of interleukin-6 (IL-6) and its soluble receptor alpha in cartilage metabolism, we analyzed their effects on tissue inhibitor of metalloproteases (TIMP) synthesis by synoviocytes and chondrocytes. TIMP-1 production by isolated human articular synovial fibroblasts and chondrocytes, stimulated by IL-6 and/or its soluble receptor, was first assayed by specific enzyme-linked immunosorbent assay; the slight stimulatory effect of IL-6 on TIMP-1 production by both types of cells was markedly amplified by the addition of soluble receptor, the maximal secretion being observed only at 96 h. TIMP-1 mRNA expression, determined by ribonuclease protection assay, was induced by IL-6 together with its soluble receptor, but TIMP-2 and -3 mRNAs were not affected by these factors. A specific neutralizing antibody abolished the effects of the soluble receptor. Finally, supernatant from synoviocytes stimulated by IL-6 plus its soluble receptor blocked almost completely the collagenolytic activity of supernatant from IL-1-induced synoviocytes. These observations indicate that IL-6 and its soluble receptor have a protective role in the metabolism of cartilage. Given the high levels of soluble receptor in synovial fluid and the marked induction of IL-6 by IL-1 or TNF-alpha, it is likely that IL-6 and its soluble receptor are critical in controlling the catabolic effects of pro-inflammatory cytokines.

Activation of tissue inhibitor of metalloproteinases-3 (TIMP-3) mRNA expression in scleroderma skin fibroblasts

Excessive accumulation of fibrillar collagens is a hallmark of the cutaneous fibrosis in both systemic and localized scleroderma. Turnover of the collagenous extracellular matrix is dependent on the balance between collagenolytic matrix metalloproteinases and their specific inhibitors. We have examined the expression of the novel, matrix associated tissue inhibitor of metalloproteinases-3 (TIMP-3) in normal and scleroderma skin fibroblasts in culture and in vivo. The levels of TIMP-3 mRNA were elevated up to 2.5-fold in five of seven systemic sclerosis fibroblast strains, whereas TIMP-1 mRNA expression was elevated up to 1.8-fold in two and TIMP-2 mRNA expression up to 1.8-fold in two systemic sclerosis strains. Using in situ hybridization, TIMP-3 mRNA was detected in seven of 12 localized scleroderma skin samples, specifically in fibroblasts within fibrotic collagen fibers or in the vicinity of inflammatory cells. TIMP-1 mRNA was detected in three of eight scleroderma skin samples in fibroblasts adjacent to inflammatory cells. The expression of TIMP-3 mRNA by systemic sclerosis and normal skin fibroblasts was enhanced to a similar extent (by 8.6- and 8.1-fold, respectively) by transforming growth factor-beta, and suppressed down to 34 and 54%, respectively, by tumor necrosis factor-alpha. Specific activation of TIMP-3 gene expression in scleroderma skin fibroblasts in culture and in vivo suggests a role for TIMP-3 in the pathogenesis of dermal fibrosis via inhibition of turnover of fibrotic dermal extracellular matrix, possibly due to upregulation of TIMP-3 expression by transforming growth factor-beta.

Temporal and spatial regulation of gene expression mediated by the promoter for the human tissue inhibitor of metalloproteinases-3 (TIMP-3)-encoding gene

A complex interplay between enzymes involved in extracellular matrix formation and their inhibitors is thought to control organogenesis during mammalian development. Disturbance of this balance may result in a wide range of diseases, including macular degeneration, arthritis, and tumor metastases. In order to define elements which may be involved in regulating human tissue inhibitor of metalloproteinase 3 (TIMP3) expression, we isolated and sequenced a clone containing 1315 bp of the 5'-upstream region of the human TIMP-3-encoding gene. A 1.2 kb fragment of this clone, which contains multiple motifs which are binding sites for known transcription factors, was used to drive expression of the lacZ reporter gene in multiple lines of transgenic mice. TIMP3 promoter activity, detected through beta-galactosidase histochemical assay, was observed at high levels in selected tissues, the identity of which varied according to developmental stage. TIMP3 promoter activity was detected at embryonic and early postnatal stages in tissues undergoing extensive remodeling, such as developing somites, bones and joints, choroid plexus, webs between the digits, and the spongiotrophoblastic portion of the placenta. In adulthood, TIMP3 promoter activity was restricted to a few tissues which exhibit high metabolic activity or rapid turnover. These include the retinal pigment epithelium (RPE), cells of the kidney cortex, hair follicles, gingiva, ovarian follicles, and testis. The results suggest that TIMP3 expression plays an active role in developmental patterning and in the maintenance of specific differentiated tissues.

Transcriptional activity of the human tissue inhibitor of metalloproteinases 1 (TIMP-1) gene in fibroblasts involves elements in the promoter, exon 1 and intron 1

The active forms of all of the matrix metalloproteinases (MMPs) are inhibited by a family of specific inhibitors, the tissue inhibitors of metalloproteinases (TIMPs). Inhibition represents a major level of control of MMP activity. A detailed knowledge of the mechanisms controlling TIMP gene expression is therefore important. We have isolated a genomic clone of the human TIMP-1 gene. A 3 kbp XbaI fragment has been sequenced; this fragment contains 1718 bp 5' flanking sequences, exon 1, a 929 bp intron 1 and part of exon 2. Computer analysis reveals 10 consensus sequences for Sp1, six for activating protein 1 (AP-1), six for polyoma enhancer A3 (PEA3), 12 for AP-2 and five CCAAT boxes. The region hybridizing with a murine TIMP-1 promoter fragment has been subcloned and analysed further. RNase protection identifies six transcription start points, making exon 1 up to 48 bp in length. Transient transfection of promoter-chloramphenicol O-acetyltransferase reporter constructs into primary human connective tissue fibroblasts shows that a 904 bp fragment that hybridizes to a murine TIMP-1 promoter fragment contains a functional promoter. Constructs of -738/+95 to -194/+21 are inducible with serum or phorbol ester to a similar extent to the endogenous TIMP-1 gene. These results and further mapping with 5' deletion mutants from the -738/+95 region have demonstrated that an AP-1 site at -92/-86 is essential for basal expression of the gene. Point mutations within this region have further confirmed the role of this site, along with a more minor role for a neighbouring PEA3 site, in basal expression. Deletions from the 3' end also implicate a region across the exon 1/intron 1 boundary and especially +21 to +58 in basal expression. The +21/+58 region contains a putative binding site for the transcription factor leader-binding protein 1 (LBP-1). Gel-shift analysis shows that protein binds specifically to this region, but competition studies suggest that it is unlikely to be LBP-1.

Differential functional significance of AP-1 binding sites in the promoter of the gene encoding mouse tissue inhibitor of metalloproteinases-3

Tissue inhibitor of metalloproteinases-3 (TIMP-3) is an extracellular-matrix-associated protein that suppresses tumorigenicity or invasion in several model systems. We have identified, by in vitro footprinting, six AP-1 (activator protein-1) or AP-1-like binding sites in the mouse TIMP-3 promoter that bind purified c-Jun homodimers. Electrophoretic mobility shift assays revealed that the non-consensus fifth AP-1 binding site (AP-720; nt -720 to -714) had the strongest binding activity for recombinant c-Jun protein, and that the fourth binding site (AP-763; nt -763 to -754) and AP-720 showed strong binding activity for cellular nuclear proteins. Antibody supershift and blocking experiments suggest that AP-720, but not AP-763, binds authentic AP-1 components. Transient transfection reporter assays of deletion constructs showed that the region spanning AP-720 has the highest transcriptional activity, and that sequences 5' to this region (nt -2846 to -747) may contain negative regulatory elements. The deletion construct containing about 500 nt 5' to the transcriptional start, but no AP-1 sites, showed lower but significant activity, suggesting both AP-1-dependent and -independent regulation of the mouse TIMP-3 promoter. Mutational inactivation of AP-720 abolished the activity increment that distinguished the reporter construct containing both AP-720 and sixth AP-1 binding site (AP-617; nt -617 to -611) from that containing only AP-617. In summary, we report here that both AP-1 and non-AP-1 elements contribute to activity, with the non-consensus AP-1 site at -720 showing the greatest functional significance among the AP-1 sites.

Structural and functional analysis of the chick chondroitin sulfate proteoglycan (aggrecan) promoter and enhancer region

Aggrecan is a large chondroitin sulfate proteoglycan, the expression of which is both tissue-specific and developmentally regulated. Here we report the cloning and sequencing of the 1.8-kilobase genomic 5' flanking sequence of the chick aggrecan gene and provide a functional and structural characterization of its promoter and enhancer region. Sequence analysis reveals potential Sp1, AP2, and NF-I related sites, as well as several putative transcription factor binding sites, including the cartilage-associated silencers CIIS1 and CIIS2. A number of these transcription factor binding motifs are embedded in a sequence flanked by prominent inverted repeats. Although lacking a classic TATA box, there are two instances in the 1.8-kb genomic fragment of TATA-like TCTAA sequences, as have been defined previously in other promoter regions. Primer extension and S1 protection analyses reveal three major transcription start sites, also located between the inverted repeats. Transient transfections of chick sternal chondrocytes and fibroblasts with reporter plasmids bearing progressively reduced portions of the aggrecan promoter region allowed mapping of chondrocyte-specific transcription enhancer and silencer elements that are consistent with the sequence analysis. These findings suggest the importance of this regulatory region in the tissue-specific expression of the chick aggrecan gene.

Tissue inhibitors of metalloproteinases in liver fibrosis

Liver fibrosis and its end stage sequelae cirrhosis represent a major worldwide health problem. By definition progressive fibrosis occurs when the rate of matrix synthesis exceeds matrix degradation. Considerable evidence suggests that the hepatic stellate cell is central to the fibrotic process. During liver injury these cells transform from a quiescent retinoid filled phenotype to a proliferative myofibroblast like cell. In this 'activated' phenotype the HSC is the major source of the interstitial collagens, which characterize fibrosis. Recent work suggests that the HSCs are also a source of matrix degrading metalloproteinase (MMPs), indicating that, together with other cells, hepatic stellate cells (HSC) could participate in matrix remodelling. However, HSC activation in tissue culture models and in vivo is also associated with expression of the powerful MMP inhibitors: tissue inhibitors of metalloproteinases 1 and 2 (TIMP-1 and TIMP-2). TIMP expression has also been demonstrated in fibrotic human liver disease and animal models of liver fibrosis. TIMPs 1 and 2 may therefore promote progression of hepatic fibrosis through inhibition of matrix degradation.

Hormonal regulation of tissue inhibitors of metalloproteinases during follicular development in the rat ovary

Tissue inhibitors of metalloproteinases (TIMPs) are membres of a multigene family of proteinase inhibitors that regulate the activity of metalloproteinases. To test the hypothesis that TIMPs regulate connective tissue remodeling during follicular development, rats were injected with PMSG (20 IU, sc), and ovaries and serum were collected at the time of pregnant mare serum gonadotropin at the time of pregnant mare serum gonadotropin (PMSG) administration (0 h) and at 6, 12, 24, 36, and 48 h later for analysis of TIMP expression, metalloproteinase inhibitor activity, and steroidogenesis. Serum estradiol levels increased from 20.9 pg/mL at 0 h to 461 pg/mL at 48 h. Northern analysis was performed for analysis of TIMP-1, TIMP-2, and TIMP-3 expression (N = 4). For TIMP-1, PMSG stimulated a 2.4- to 2.5-fold increase in TIMP-1 mRNA at 6 and 12 h compared to ovaries collected at the time of PMSG administration (i.e., 0 h control). TIMP-1 mRNA returned to control levels within 24 h and remained unchanged through 48 h. In contrast to TIMP-1, TIMP-3 mRNA decreased by approx 2.5-fold at 6 h following PMSG administration, and expression remained decreased through 48 h. For TIMP-2, the expression of the 3.5-kb transcript decreased at 24 h after PMSG, whereas expression of the 1 kb transcript was unchanged. There was no change in metalloproteinase inhibitor activity in whole ovarian extracts between 0 and 36 h. However, there was an increase in inhibitor activity at 48 h. These findings are the first demonstration of hormonal regulation of TIMPs during the follicular phase. The differential regulation of the TIMPs by gonadotropins, for example, an increase in TIMP-1 and a concomitant decrease in TIMP-3 expression, may reflect different roles, sites of action, or enzyme specificity for the inhibitors as the follicle grows.

Regulation of tissue inhibitor of metalloproteinases-3 gene expression by transforming growth factor-beta and dexamethasone in bovine and human articular chondrocytes

Physiological and pathological degradation of cartilage extracellular matrix (ECM) is regulated by the balance between tissue inhibitors of metalloproteinases (TIMPs) and matrix metalloproteinases (MMPs). We examined the potential of chondrocytes from normal bovine or human osteoarthritic (OA) cartilage to express RNA for the new inhibitor TIMP-3 and studied its regulation by an inducer of matrix synthesis, transforming growth factor-beta (TGF-beta). Freshly released chondrocytes constitutively expressed three transcripts of TIMP-3 that are induced by serum factors. In primary cultures of chondrocytes, one of these factors, TGF-beta, increased TIMP-3 mRNA in a dose-dependent fashion that required de novo protein synthesis and transcription. TGF-beta did not alter stability of the TIMP-3 transcripts in RNA decay time-courses, suggesting a transcriptional control. Nuclear run-on assays confirmed increased rate of TIMP-3 gene transcription by TGF-beta. An antiinflammatory glucocorticoid, dexamethasone, inhibited the basal, and suppressed partially the TGF-beta-inducible, TIMP-3 expression in primary bovine and human chondrocytes. DNA sequencing of bovine TIMP-3 cDNA revealed an open reading frame of a 211-amino-acid protein containing signal peptide and 12 conserved cysteines. The encoded protein differed from human TIMP-3 at four positions. The constitutive expression and evolutionary conservation of TIMP-3 imply its important function. TIMP-3 induction by TGF-beta suggests the role of this factor and TIMP-3 in cartilage remodeling with important implications for arthritis.

Structure and characterization of the human tissue inhibitor of metalloproteinases-2 gene

We report here the characterization of the human tissue inhibitor of metalloproteinases-2 (TIMP-2) gene. The gene is 83 kilobase pairs (kb) long with exon-intron splicing sites located in preserved positions among the three members of the TIMP family. A 2.6-kb genomic DNA fragment flanking the 5'-end of the gene contains several regulatory elements including five Sp1, two AP-2, one AP-1, and three PEA-3 binding sites. Despite the presence of a complete AP-1 consensus at position -281, the promoter did not respond to 12-O-tetradecanoylphorbol-13-acetate treatment. However, 12-O-tetradecanoylphorbol-13-acetate response was generated by insertion of a similar AP-1 consensus at position -71, indicating the importance of the positioning of this motif. The promoter contains a typical CpG island; however, methylation of this island did not seem to influence gene expression. Analysis of the 3'-end of the gene revealed that the two mRNAs for TIMP-2 (1.2 and 3.8 kb) differ by the selection of their polyadenylation signal sites, but selection of these sites does not affect RNA stability. In summary, the TIMP-2 gene has several features observed in housekeeping genes, and differs significantly from TIMP-1 and TIMP-3 genes. These differences are likely to explain the specific roles that these inhibitors play in the regulation of matrix metalloproteinases.

Oncostatin M differentially regulates tissue inhibitors of metalloproteinases TIMP-1 and TIMP-3 gene expression in human synovial lining cells

Tissue inhibitor of metalloproteinases (TIMP) 1, 2 and 3 are related proteins that can form complexes with all known matrix metalloproteinases (MMPs). They inhibit the action of MMPs on extracellular matrix components. The balance of MMPs and TIMPs is important for tissue remodeling and its disturbance is believed to play a crucial role in pathophysiological processes such as tumor metastasis, destruction of cartilage and fibrosis. Cytokines and growth factors were found to regulate TIMPs and MMPs in a complex manner. In order to better understand the role of TIMPs in inflammatory joint diseases we have studied in vitro the regulation of TIMP-1 and TIMP-3 by inflammatory cytokines in cultured human synovial lining cells. We found that transforming growth factor beta 1 as well as interleukin-1 beta induce gene expression of both TIMP-1 and TIMP-3. In contrast, oncostatin M, an interleukin-6-type cytokine produced by activated T-lymphocytes and monocytes, had a differential effect on TIMP mRNA levels. After oncostatin M treatment, TIMP-1 expression was up-regulated but basal, as well as interleukin-1 beta-induced, TIMP-3 expression was inhibited. Interleukin-6 itself had no effect on synovial lining cells but a complex of interleukin-6 and the soluble interleukin-6 receptor induced activation of signal transducer and activator of transcription (STAT) factors in these cells and regulated TIMP-1 and TIMP-3 expression in a similar fashion as oncostatin M. Since TIMP-3 is matrix-associated whereas TIMP-1 is found in many body fluids, the role of oncostatin M during inflammatory processes might be to promote ECM degradation in the local environment but to prevent it systemically.