Expression, purification and characterization of recombinant mouse MT5-MMP protein products

Identification of binding partners that facilitate membrane-type 5 matrix metalloproteinase (MT5-MMP) processing of amyloid precursor protein

One of the pathological hallmarks of Alzheimer's disease (AD) is the presence of extracellular deposits of amyloid beta (Aβ) peptide. In addition to Aβ as the core component of the amyloid plaque, the amyloid precursor protein (APP) processing fragment Aβ was also found accumulated around the plaque. The APPη pathway, mainly mediated by membrane-type 5 matrix metalloproteinase (MT5-MMP), represents an important factor in AD pathogenesis. The proamyloidogenic features of MT5-MMP could result from interactions with APP when trafficking between organelles, so determination of the location within the cell of APPη cleavage and interacting proteins of MT5-MMP affecting this process will be of priority in understanding the role of MT5-MMP in AD. In the present study, MT5-MMP was found to be located in the nucleus, cytosol, and cytosolic subcellular granules of CHO cells that stably expressed wild-type human APP751. MT5-MMP fusion proteins were constructed that could localize enzyme production in the Golgi apparatus, endosome, ER, mitochondria, or plasma membrane. The fusion proteins significantly increased sAPPη when directed to the endosome, Golgi apparatus, plasma membrane, or mitochondria. Since the C-terminal region of MT5-MMP is responsible for its intracellular location and trafficking, this domain was used as the bait in a yeast two-hybrid screen to identify MT5-MMP protein partners in a human brain cDNA library. Identified binding partners included N4BP2L1, TMX3, EIG121, bridging Integrator 1 (BIN1), RUFY4, HTRA1, and TMEM199. The binding of N4BP2L1, EIG121, BIN1, or TMX3 to MT5-MMP resulted in the most significant increase in sAPPη production. Thus, the action of MT5-MMP on APP occurs in multiple locations within the cell and is facilitated by site-specific binding partners.

Current Perspectives on the Role of Matrix Metalloproteinases in the Pathogenesis of Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common skin malignancy, which rarely metastasizes but has a great ability to infiltrate and invade the surrounding tissues. One of the molecular players involved in the metastatic process are matrix metalloproteinases (MMPs). MMPs are enzymes that can degrade various components of the extracellular matrix. In the skin, the expression of MMPs is increased in response to various stimuli, including ultraviolet (UV) radiation, one of the main factors involved in the development of BCC. By modulating various processes that are linked to tumor growth, such as invasion and angiogenesis, MMPs have been associated with UV-related carcinogenesis. The sources of MMPs are multiple, as they can be released by both neoplastic and tumor microenvironment cells. Inhibiting the action of MMPs could be a useful therapeutic option in BCC management. In this review that reunites the latest advances in this domain, we discuss the role of MMPs in the pathogenesis and evolution of BCC, as molecules involved in tumor aggressiveness and risk of recurrence, in order to offer a fresh and updated perspective on this field.

Emerging Alternative Proteinases in APP Metabolism and Alzheimer's Disease Pathogenesis: A Focus on MT1-MMP and MT5-MMP

Processing of amyloid beta precursor protein (APP) into amyloid-beta peptide (Aβ) by β-secretase and γ-secretase complex is at the heart of the pathogenesis of Alzheimer’s disease (AD). Targeting this proteolytic pathway effectively reduces/prevents pathology and cognitive decline in preclinical experimental models of the disease, but therapeutic strategies based on secretase activity modifying drugs have so far failed in clinical trials. Although this may raise some doubts on the relevance of β- and γ-secretases as targets, new APP-cleaving enzymes, including meprin-β, legumain (δ-secretase), rhomboid-like protein-4 (RHBDL4), caspases and membrane-type matrix metalloproteinases (MT-MMPs/η-secretases) have confirmed that APP processing remains a solid mechanism in AD pathophysiology. This review will discuss recent findings on the roles of all these proteinases in the nervous system, and in particular on the roles of MT-MMPs, which are at the crossroads of pathological events involving not only amyloidogenesis, but also inflammation and synaptic dysfunctions. Assessing the potential of these emerging proteinases in the Alzheimer’s field opens up new research prospects to improve our knowledge of fundamental mechanisms of the disease and help us establish new therapeutic strategies.

Vitamin D in Synaptic Plasticity, Cognitive Function, and Neuropsychiatric Illness

Over a billion people worldwide are affected by vitamin D deficiency. Although vitamin D deficiency is associated with impaired cognition, the mechanisms mediating this link are poorly understood. The extracellular matrix (ECM) has now emerged as an important participant of synaptic plasticity and a new hypothesis is that vitamin D may interact with aggregates of the ECM, perineuronal nets (PNNs), to regulate brain plasticity. Dysregulation of PNNs caused by vitamin D deficiency may contribute to the presentation of cognitive deficits. Understanding the molecular mechanisms underpinning the role of vitamin D in brain plasticity and cognition could help identify ways to treat cognitive symptoms in schizophrenia and other neuropsychiatric conditions.

Expression and Purification of Matrix Metalloproteinases in Escherichia coli

The MMP (matrix metalloproteinases) family of endopeptidases are involved in cleavage induced remodelling of the extracellular matrix including collagen, fibrinogen, elastin, and gelatin. Owing to their proteolytic activity which can cleave and degrade multiple intracellular substrates, the overexpression and purification of these proteins tends to be toxic. Here we describe a novel "matrix assisted refolding" protocol to overcome the technical challenges associated with overexpression and purification of full-length MMPs. The toxicity issue associated with MMP expression, is circumvented by expressing the recombinant protein in Escherichia coli in an inactive insoluble form. The methodology used for obtaining full-length MMP2 protein from these inclusion bodies, by its subsequent purification and refolding using affinity chromatography, through a single-step matrix based refolding protocol is presented here. The protocol described yields high concentrations of pure full-length and active MMP2 protein useful for downstream applications.

Membrane-type matrix metalloproteinases: Their functions and regulations

Membrane-type matrix metalloproteinases (MT-MMPs) form a subgroup of the matrix metalloproteinase (MMP) family, and there are 6 MT-MMPs in humans. MT-MMPs are further sub-classified into type I transmembrane-type (MT1, -MT2-, MT3- and MT5-MMPs) and glycosylphosphatidylinositol (GPI)-anchored type (MT4- and MT6-MMPs). In either case MT-MMPs are tethered to the plasma membrane, and this cell surface expression provides those enzymes with unique functionalities affecting various cellular behaviours. Among the 6 MT-MMPs, MT1-MMP is the most investigated enzyme and many of its roles and regulations have been revealed to date, but the potential roles and regulatory mechanisms of other MT-MMPs are gradually getting clearer as well. Further investigations of MT-MMPs are likely to reveal novel pathophysiological mechanisms and potential therapeutic strategies for different diseases in the future.

Dysregulated expression of matrix metalloproteinases and their inhibitors may participate in the pathogenesis of pre-eclampsia and fetal growth restriction

BACKGROUND

Trophoblast invasion into the maternal endometrium serves an important function in human pregnancy. Dysregulation of the finely controlled process of trophoblast invasion can result in a wide spectrum of pregnancy abnormalities.

AIMS

We aimed to elucidate the relationship between the expression of matrix metalloproteinases and pregnancy complication.

STUDY DESIGN

The study group consisted of placental bed biopsy tissues obtained from normal vaginal deliveries (N=15), normal cesarean deliveries (N=15), pre-eclampsia (N=24) and fetal growth restriction (FGR) (N=10). We evaluated the expressions of MMP-2, -8, -9, -11, -19, -15 (MT2-MMP), -16 (MT3-MMP), and -24 (MT5-MMP), as well as TIMP-1 and -3, by applying Western blot and immunohistochemistry methods.

SUBJECTS

Human placental tissues were used for this study.

OUTCOME MEASURES

The expressions of MMP-2, -8, -9, -11, -19, -15 (MT2-MMP), -16 (MT3-MMP), and -24 (MT5-MMP), as well as TIMP-1 and -3 in human placenta tissues.

RESULTS

Compared with those in normal pregnancies, the expression of MMP-2, -8, -9 and -11 was downregulated in villous tissues of pre-eclampsia and FGR cases (p<0.05). TIMP-1 and -3 were increased in pre-eclampsia and FGR (p<0.05). No significant difference was found between normal vaginal deliveries and cesarean deliveries.

CONCLUSIONS

We speculate that the change in invasion-associated proteinase expression will affect placental development and may thus contribute to the development of complicated pregnancies.

Perineuronal nets and schizophrenia: the importance of neuronal coatings

Schizophrenia is a complex brain disorder associated with deficits in synaptic connectivity. The insidious onset of this illness during late adolescence and early adulthood has been reported to be dependent on several key processes of brain development including synaptic refinement, myelination and the physiological maturation of inhibitory neural networks. Interestingly, these events coincide with the appearance of perineuronal nets (PNNs), reticular structures composed of components of the extracellular matrix that coat a variety of cells in the mammalian brain. Until recently, the functions of the PNN had remained enigmatic, but are now considered to be important in development of the central nervous system, neuronal protection and synaptic plasticity, all elements which have been associated with schizophrenia. Here, we review the emerging evidence linking PNNs to schizophrenia. Future studies aimed at further elucidating the functions of PNNs will provide new insights into the pathophysiology of schizophrenia leading to the identification of novel therapeutic targets with the potential to restore normal synaptic integrity in the brain of patients afflicted by this illness.

Anthrax toxin receptor 2 promotes human uterine smooth muscle cell viability, migration and contractility

OBJECTIVE

Previously we demonstrated anthrax toxin receptor 2 knockout (Antxr2(-/-)) mice are fertile but fail to deliver their pups at term. This parturition defect is associated with overaccumulation of extracellular matrix proteins and decreased myometrial cell content in the uterus. Myometrial cell loss in Antxr2(-/-) uterine tissue prompted us to evaluate if ANTXR2 is essential for human uterine smooth muscle cell viability and function.

STUDY DESIGN

We subjected human uterine smooth muscle cell to lentiviral-mediated knock down or retroviral-mediated overexpression of ANTXR2. Flow cytometry confirmed lentiviral-mediated knock down or retroviral-mediated overexpression in cell lines vs control. Cell behavior and function in control, lentiviral-mediated knock down and retroviral-mediated overexpression cells were evaluated for apoptosis via TUNEL assay, migration via Boyden chamber assay and with oxytocin-mediated collagen contraction assays. Matrix metalloproteinase activity was evaluated using gelatin zymography. Cell lines and samples were run in duplicate. Student t test was used for statistical analysis.

RESULTS

ANTXR2 is expressed by human uterine smooth muscle cell. Human uterine smooth muscle cell-lentiviral-mediated knock down cells exhibited increased apoptosis (P < .05) and decreased migration (P < .05), although human uterine smooth muscle cell-retroviral-mediated overexpression cells exhibited no change in apoptosis (P = .91) and increased migration (P = .05) vs control. Human uterine smooth muscle cell-lentiviral-mediated knock down cells contracted significantly less than control, although human uterine smooth muscle cell-retroviral-mediated overexpression cells showed no difference in contractility vs control. Matrix metalloproteinase activity 2 activity appeared slightly decreased in human uterine smooth muscle cell-lentiviral-mediated knock down cells and increased in human uterine smooth muscle cell-retroviral-mediated overexpression cells vs control.

CONCLUSION

ANTXR2 is expressed by human uterine smooth muscle cell and appears important for normal human uterine smooth muscle cell viability, migration and contractility. Further studies are needed to delineate if ANTXR2 is important for normal and abnormal labor patterns.

MT5-MMP, ADAM-10, and N-cadherin act in concert to facilitate synapse reorganization after traumatic brain injury

Matrix metalloproteinases (MMPs) influence synaptic recovery following traumatic brain injury (TBI). Membrane type 5-matrix metalloproteinase (MT5-MMP) and a distintegrin and metalloproteinase-10 (ADAM-10) are membrane-bound MMPs that cleave N-cadherin, a protein critical to synapse stabilization. This study examined protein and mRNA expression of MT5-MMP, ADAM-10, and N-cadherin after TBI, contrasting adaptive and maladaptive synaptogenesis. The effect of MMP inhibition on MT5-MMP, ADAM-10, and N-cadherin was assessed during maladaptive plasticity and correlated with synaptic function. Rats were subjected to adaptive unilateral entorhinal cortical lesion (UEC) or maladaptive fluid percussion TBI+bilateral entorhinal cortical lesion (TBI+BEC). Hippocampal MT5-MMP and ADAM-10 protein was significantly elevated 2 and 7 days post-injury. At 15 days after UEC, each MMP returned to control level, while TBI+BEC ADAM-10 remained elevated. At 2 and 7 days, N-cadherin protein was below control. By the 15-day synapse stabilization phase, UEC N-cadherin rose above control, a shift not seen for TBI+BEC. At 7 days, increased TBI+BEC ADAM-10 transcript correlated with protein elevation. UEC ADAM-10 mRNA did not change, and no differences in MT5-MMP or N-cadherin mRNA were detected. Confocal imaging showed MT5-MMP, ADAM-10, and N-cadherin localization within reactive astrocytes. MMP inhibition attenuated ADAM-10 protein 15 days after TBI+BEC and increased N-cadherin. This inhibition partially restored long-term potentiation induction, but did not affect paired-pulse facilitation. Our results confirm time- and injury-dependent expression of MT5-MMP, ADAM-10, and N-cadherin during reactive synaptogenesis. Persistent ADAM-10 expression was correlated with attenuated N-cadherin level and reduced functional recovery. MMP inhibition shifted ADAM-10 and N-cadherin toward adaptive expression and improved synaptic function.

Anthrax toxin receptor 2 functions in ECM homeostasis of the murine reproductive tract and promotes MMP activity

Anthrax Toxin Receptor proteins function as receptors for anthrax toxin, however physiological activity remains unclear. To evaluate the biological role of Antxr2, we generated Antxr2-/- mice. Antxr2-/- mice were viable, however Antxr2 is required for parturition in young females and for preserving fertility in older female mice. Histological analysis of the uterus and cervix revealed aberrant deposition of extracellular matrix proteins such as type I collagen, type VI collagen and fibronectin. A marked disruption of both the circular and longitudinal myometrial cell layers was evident in Antxr2-/- mice. These changes progressed as the mice aged, resulting in a thickened, collagen dense, acellular stroma and the disappearance of normal uterine architecture. To investigate the molecular mechanism underlying the uterine fibrosis we performed immunoblotting for MMP2 using uterine lysates and zymography using conditioned medium from Antxr2-/- mouse embryonic fibroblasts and found reduced levels of activated MMP2 in both. This prompted us to investigate MT1-MMP status, as MMP2 processing is regulated by MT1-MMP. We found MT1-MMP activity, as measured by MMP2 processing and activation, was enhanced by expression of either ANTXR1 or ANTXR2. We identified an ANTXR2/MT1-MMP complex and demonstrated that MT1-MMP activity is dependent on ANTXR2 expression levels in cells. Thus, we have discovered that ANTXR1 and ANTXR2 function as positive regulators of MT1-MMP activity.

Human matrix metalloproteinases: an ubiquitarian class of enzymes involved in several pathological processes

Human matrix metalloproteinases (MMPs) belong to the M10 family of the MA clan of endopeptidases. They are ubiquitarian enzymes, structurally characterized by an active site where a Zn(2+) atom, coordinated by three histidines, plays the catalytic role, assisted by a glutamic acid as a general base. Various MMPs display different domain composition, which is very important for macromolecular substrates recognition. Substrate specificity is very different among MMPs, being often associated to their cellular compartmentalization and/or cellular type where they are expressed. An extensive review of the different MMPs structural and functional features is integrated with their pathological role in several types of diseases, spanning from cancer to cardiovascular diseases and to neurodegeneration. It emerges a very complex and crucial role played by these enzymes in many physiological and pathological processes.

New Strategies for the Next Generation of Matrix-Metalloproteinase Inhibitors: Selectively Targeting Membrane-Anchored MMPs with Therapeutic Antibodies

MMP intervention strategies have met with limited clinical success due to severe toxicities. In particular, treatment with broad-spectrum MMP-inhibitors (MMPIs) caused musculoskeletal pain and inflammation. Selectivity may be essential for realizing the clinical potential of MMPIs. Here we review discoveries pinpointing membrane-bound MMPs as mediators of mechanisms underlying cancer and inflammation and as possible therapeutic targets for prevention/treatment of these diseases. We discuss strategies to target these therapeutic proteases using highly selective inhibitory agents (i.e., human blocking antibodies) against individual membrane-bound MMPs.

Physiology and pathophysiology of matrix metalloproteases

Matrix metalloproteases (MMPs) comprise a family of enzymes that cleave protein substrates based on a conserved mechanism involving activation of an active site-bound water molecule by a Zn(2+) ion. Although the catalytic domain of MMPs is structurally highly similar, there are many differences with respect to substrate specificity, cellular and tissue localization, membrane binding and regulation that make this a very versatile family of enzymes with a multitude of physiological functions, many of which are still not fully understood. Essentially, all members of the MMP family have been linked to disease development, notably to cancer metastasis, chronic inflammation and the ensuing tissue damage as well as to neurological disorders. This has stimulated a flurry of studies into MMP inhibitors as therapeutic agents, as well as into measuring MMP levels as diagnostic or prognostic markers. As with most protein families, deciphering the function(s) of MMPs is difficult, as they can modify many proteins. Which of these reactions are physiologically or pathophysiologically relevant is often not clear, although studies on knockout animals, human genetic and epigenetic, as well as biochemical studies using natural or synthetic inhibitors have provided insight to a great extent. In this review, we will give an overview of 23 members of the human MMP family and describe functions, linkages to disease and structural and mechanistic features. MMPs can be grouped into soluble (including matrilysins) and membrane-anchored species. We adhere to the 'MMP nomenclature' and provide the reader with reference to the many, often diverse, names for this enzyme family in the introduction.

Expression and purification of membrane-type MMPs

Matrix metalloproteinases (MMPs) modulate cell-cell and cell-matrix interactions and the membrane-type MMPs (MT-MMPs) are especially important for pericellular proteolysis. Understanding the activity, regulation, and function of MT-MMPs would provide important insight for ongoing research in many diseases including cancer, fibrosis, and autoimmune diseases. In this chapter, we introduce the methods to express and purify recombinant MT-MMPs using Escherichia coli or mammalian cells, as well as how to detect the activity of MT-MMPs in proMMP-2 activation using gelatin zymography.

Metalloproteinase MT5-MMP is an essential modulator of neuro-immune interactions in thermal pain stimulation

Peripheral interactions between nociceptive fibers and mast cells contribute to inflammatory pain, but little is known about mechanisms mediating neuro-immune communication. Here we show that metalloproteinase MT5-MMP (MMP-24) is an essential mediator of peripheral thermal nociception and inflammatory hyperalgesia. We report that MT5-MMP is expressed by CGRP-containing peptidergic nociceptors in dorsal root ganglia and that Mmp24-deficient mice display enhanced sensitivity to noxious thermal stimuli under basal conditions. Consistently, mutant peptidergic sensory neurons hyperinnervate the skin, a phenotype that correlates with changes in the regulated cleavage of the cell-cell adhesion molecule N-cadherin. In contrast to basal nociception, Mmp24(-/-) mice do not develop thermal hyperalgesia during inflammation, a phenotype that appears associated with alterations in N-cadherin-mediated cell-cell interactions between mast cells and sensory fibers. Collectively, our findings demonstrate an essential role of MT5-MMP in the development of dermal neuro-immune synapses and suggest that this metalloproteinase may be a target for pain control.

Loss of Perineuronal Net in ME7 Prion Disease

Microglial activation and behavioral abnormalities occur before neuronal loss in experimental murine prion disease; the behavioral changes coincide with a reduction in synaptic plasticity. Because synaptic plasticity depends on an intact perineuronal net (PN), a specialized extracellular matrix that surrounds parvalbumin (PV)-positive GABAergic (gamma-aminobutyric acid [GABA]) inhibitory interneurons, we investigated the temporal relationships between microglial activation and loss of PN and PV-positive neurons in ME7 murine prion disease. Anesthetized C57Bl/6J mice received bilateral intracerebral microinjections of ME7-infected or normal brain homogenate into the dorsal hippocampus. Microglial activation, PrP accumulation, the number of PV-positive interneurons, and Wisteria floribunda agglutinin-positive neurons (i.e. those with an intact PN) were assessed in the ventral CA1 and subiculum at 4, 8, 12, 16, and 20 weeks postinjection. Hippocampal areas and total neuron numbers in the ventral CA1 and subiculum were also determined. Loss of PN coincided with early microglial activation and with a reduction in synaptic plasticity. No significant loss of PV-positive interneurons was observed. Our findings suggest that the substrate of the earliest synaptic and behavioral abnormalities in murine prion disease may be inflammatory microglia-mediated degradation of the PN.

Leukocyte cell surface proteinases: regulation of expression, functions, and mechanisms of surface localization

A number of proteinases are expressed on the surface of leukocytes including members of the serine, metallo-, and cysteine proteinase superfamilies. Some proteinases are anchored to the plasma membrane of leukocytes by a transmembrane domain or a glycosyl phosphatidyl inositol (GPI) anchor. Other proteinases bind with high affinity to classical receptors, or with lower affinity to integrins, proteoglycans, or other leukocyte surface molecules. Leukocyte surface levels of proteinases are regulated by: (1) cytokines, chemokines, bacterial products, and growth factors which stimulate synthesis and/or release of proteinases by cells; (2) the availability of surface binding sites for proteinases; and/or (3) internalization or shedding of surface-bound proteinases. The binding of proteinases to leukocyte surfaces serves many functions including: (1) concentrating the activity of proteinases to the immediate pericellular environment; (2) facilitating pro-enzyme activation; (3) increasing proteinase stability and retention in the extracellular space; (4) regulating leukocyte function by proteinases signaling through cell surface binding sites or other surface proteins; and (5) protecting proteinases from inhibition by extracellular proteinase inhibitors. There is strong evidence that membrane-associated proteinases on leukocytes play critical roles in wound healing, inflammation, extracellular matrix remodeling, fibrinolysis, and coagulation. This review will outline the biology of membrane-associated proteinases expressed by leukocytes and their roles in physiologic and pathologic processes.

Matrix metalloproteinases and proteoglycans in axonal regeneration

After an injury to the adult mammalian central nervous system (CNS), a variety of growth-inhibitory molecules are upregulated. A glial scar forms at the site of injury and is composed of numerous molecular substances, including chondroitin sulfate proteoglycans (CSPGs). These proteoglycans inhibit axonal growth in vitro and in vivo. Matrix metalloproteinases (MMPs) can degrade the core protein of some CSPGs as well as other growth-inhibitory molecules such as Nogo and tenascin-C. MMPs have been shown to facilitate axonal regeneration in the adult mammalian peripheral nervous system (PNS). This review will focus on the various roles of proteoglycans and MMPs within the injured nervous system. First, we will present a general background on the injured central nervous system and explore the roles that proteoglycans play in the injured PNS and CNS. Second, we will discuss the various functions of MMPs within the injured PNS and CNS. Special attention will be paid to the possibility of how MMPs might modify the growth-inhibitory extracellular environment of the injured adult mammalian spinal cord and facilitate axonal regeneration in the CNS.

Fibroblast extracellular matrix gene expression in response to keratinocyte-releasable stratifin

Termination of wound-healing process requires a fine balance between connective tissue deposition and its hydrolysis. Previously, we have demonstrated that keratinocyte-releasable stratifin, also known as 14-3-3 sigma protein, stimulates collagenase (MMP-1) expression in dermal fibroblasts. However, role of extracellular stratifin in regulation of extracellular matrix (ECM) factors and other matrix metalloproteinases (MMPs) in dermal fibroblast remains unexplored. To address this question, large-scale ECM gene expression profile were analyzed in human dermal fibroblasts co-cultured with keratinocytes or treated with recombinant stratifin. Superarray pathway-specific microarrays were utilized to identify upregulation or downregulation of 96 human ECM and adhesion molecule genes. RT-PCR and Western blot were used to validate microarray expression profiles of selected genes. Comparison of gene profiles with the appropriate controls showed a significant (more than twofold) increase in expression of collagenase-1, stromelysin-1 and -2, neutrophil collagenase, and membrane type 5 MMP in dermal fibroblasts treated with stratifin or co-cultured with keratinocytes. Expression of type I collagen and fibronectin genes decreased in the same fibroblasts. The results of a dose-response experiment showed that stratifin stimulates the expression of stromelysin-1 (MMP-3) mRNA by dermal fibroblasts in a concentration-dependent fashion. Furthermore, Western blot analysis of fibroblast-conditioned medium showed a peak in MMP-3 protein levels 48 h following treatment with recombinant stratifin. In a lasting-effect study, MMP-3 protein was detected in fibroblast-condition medium for up to 72 h post removal of stratifin. In conclusion, our results suggest that keratinocyte-releasable stratifin plays a major role in induction of ECM degradation by dermal fibroblasts through stimulation of key MMPs, such as MMP-1 and MMP-3. Therefore, stratifin protein may prove to be a useful target for clinical intervention in controlling excessive wound healing in fibrotic conditions.

Membrane localization of membrane type 5 matrix metalloproteinase by AMPA receptor binding protein and cleavage of cadherins

Matrix metalloproteinases (MMPs) have been proposed to remodel the extracellular environment of neurons. Here, we report that the metalloproteinase membrane-type 5 MMP (MT5-MMP) binds to AMPA receptor binding protein (ABP) and GRIP (glutamate receptor interaction protein), two related postsynaptic density (PSD) PDZ (postsynaptic density-95/Discs large/zona occludens-1) domain proteins that target AMPA receptors to synapses. The MT5-MMP C terminus binds ABP PDZ5 and the two proteins coimmunoprecipitated and colocalized in heterologous cells and neurons. MT5-MMP localized in filopodia at the tips of growth cones in young [2-5 d in vitro (DIV)] cultured embryonic hippocampal neurons, and at synapses in mature (21 DIV) neurons. Its enrichment in synaptosomes also indicated a synaptic localization in the mature brain. Deletion of the PDZ binding site impaired membrane trafficking of MT5-MMP, whereas exogenous ABP splice forms that are associated either with the plasma membrane or with the cytosol, respectively, colocalized with MT5-MMP in synaptic spines or recruited MT5-MMP to intracellular compartments. We show that endogenous MT5-MMP is found in cultured neurons and brain lysates in a proenzyme form that is activated by furin and degraded by auto-proteolysis. We also identify cadherins as MT5-MMP substrates. These results suggest that ABP directs MT5-MMP proteolytic activity to growth cones and synaptic sites in neurons, where it may regulate axon pathfinding or synapse remodeling through proteolysis of cadherins or other ECM or cell adhesion molecules.

Matrix metalloproteinases and their inhibitors in the developing mouse brain and spinal cord: a reverse transcription quantitative polymerase chain reaction study

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) are essential for coordinated extracellular matrix turnover during central nervous system development. Reverse transcription quantitative polymerase chain reaction was employed to evaluate the mRNA expression of MMP-2, -3, -7, -9, -10, -11, -12, -13, -14, -15, and -24, and TIMP-1, -2, -3, and -4 in the prosencephalon, rhombencephalon, and spinal cord of 1- to 40-week-old mice. The molecular data were interpreted in the context of morphological observations. Significantly higher expression levels of MMP-2, -11, -13, -14, -15, and -24, and TIMP-1 and -3 were found in the brain and spinal cord 1 week after birth compared to later time points, while MMP-9 and TIMP-2 upregulation was restricted to the brain. This upregulation coincided with the maximal extension of the transient cerebellar external granular layer, a marker of neuronal progenitor proliferation and migration. MMP-12 was significantly upregulated at later time points and found to be positively correlated with myelination in the rhombencephalon and spinal cord. MMP-3, -7, and -10 mRNA expressions remained unchanged or were negligible. In summary, while most of the MMPs and TIMPs studied seem to be involved in cell proliferation and migration, MMP-12 might be decisive for myelination.

Zymographic techniques for the analysis of matrix metalloproteinases and their inhibitors

The balance between matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), is largely responsible for the remodeling of tissues. Deregulation of this balance is a characteristic of extensive tissue degradation in certain degenerative diseases. To analyze the role of MMPs and TIMPs in tissue remodeling under normal and pathological conditions, it is important to have reliable detection methods. This review will focus on zymographical techniques for the analysis of MMPs and TIMPs. MMPs can be analyzed with several zymographical techniques, but substrate zymography is the most commonly used. This technique identifies MMPs by the degradation of their preferential substrate and by their molecular weight. Several substrates that can be used for zymography are described. Reverse zymography, which detects TIMPs by their ability to inhibit MMPs, is also discussed. Finally, in situ zymography is described, which is used to localize MMPs in tissue sections. Common problems encountered during sample preparation, zymography itself and the data analysis are discussed. Hints are given to improve the sensitivity and accuracy of zymographical methods. In conclusion, zymography is a valuable tool for research purposes and for the development of new diagnostic techniques and therapies for pathological conditions such as rheumatoid and osteoarthritis, and tumor progression.

The Hemopexin Domain of Membrane-type Matrix Metalloproteinase-1 (MT1-MMP) Is Not Required for Its Activation of proMMP2 on Cell Surface but Is Essential for MT1-MMP-mediated Invasion in Three-dimensional Type I Collagen

Membrane-type matrix metalloproteinase-1 (MT1-MMP) plays a key role in tumor invasion and metastasis by degrading the extracellular matrix and activating proMMP2. Here we show that the conserved hemopexin domain is required for MT1-MMP-mediated invasion and growth in three-dimensional type I collagen matrix but not proMMP2 activation. Deletion of the hemopexin domains in MT1-, MT2-, MT3-, MT5-, and MT6-MMP does not impair their abilities to activate proMMP2. In fact, hemopexin-less MT5- and MT6-MMP activate proMMP2 better than their wild type counterparts. On the other hand, hemopexin-less MT1-MMP fails to promote cell invasion into type I collagen but retains the capacity to enhance the growth of Madin-Darby canine kidney cells as cysts in three-dimensional collagen matrix. Moreover, the hemopexin domain is also required for MT1-MMP-mediated invasion/scattering of MCF-7 cells in three-dimensional collagen matrix. Because growth and invasion in a three-dimensional model may correlate with tumor invasiveness in vivo, our data suggest that the hemopexin domains of MT-MMPs should be targeted for the development of anti-cancer therapies by employing screening assays developed for three-dimensional models rather than their enzymatic activity toward proMMP2.

Matrix metalloproteinases and their endogenous inhibitors in neuronal physiology of the adult brain

More than 20 matrix metalloproteinases (MMPs) and four of their endogenous tissue inhibitors (TIMPs) act together to control tightly temporally restricted, focal proteolysis of extracellular matrix. In the neurons of the adult brain several components of the TIMP/MMP system are expressed and are responsive to changes in neuronal activity. Furthermore, functional studies, especially involving blocking of MMP activities, along with the identification of MMP substrates in the brain strongly suggest that this enzymatic system plays an important physiological role in adult brain neurons, possibly being pivotal for neuronal plasticity.

Absence of mechanical allodynia and Abeta-fiber sprouting after sciatic nerve injury in mice lacking membrane-type 5 matrix metalloproteinase

Matrix metalloproteinases (MMPs) are a family of endopeptidases that degrade extracellular matrix components. Membrane-type 5 MMP (MT5-MMP/MMP-24) was identified as neuron-specific, and is believed to contribute to neuronal circuit formation and plasticity. To elucidate its function in vivo, we have generated mice lacking MT5-MMP by gene targeting. MT5-MMP-deficient mice were born without obvious morphological abnormalities. No apparent histological defects were observed in the nervous system either. However, MT5-MMP-deficient mice did not develop neuropathic pain with mechanical allodynia after sciatic nerve injury, though responses to acute noxious stimuli were normal. Neuropathic pain induced by peripheral nerve lesions is known to accompany structural reorganization of the nervous system. Intraneural injection of cholera toxin B subunit, a transganglionic tracer, into the injured sciatic nerve of wild-type mice revealed that the myelinated Abeta-fiber primary afferents sprouted from laminae III-VI of the dorsal horn of the spinal cord and invaded lamina II. However, no such sprouting and invasion of Abeta-fibers were observed in MT5-MMP-deficient mice. These findings suggest that MT5-MMP is essential for the development of mechanical allodynia and plays an important role in neuronal plasticity in this mouse model.

Matrix metalloproteinases: contribution to pathogenesis, diagnosis, surveillance and treatment of abdominal aortic aneurysms

BACKGROUND

Aortic abdominal aneurysm (AAA) represents a common chronic degenerative disease of the aortic wall. Chronic inflammation and enzymatic degradation of elastic lamellae and extracellular matrix (ECM) proteins constitute the most prominent characteristics of AAAs. There is mounting evidence that matrix metalloproteinases (MMPs) are the predominant proteinases in the AAA wall. These enzymes represent a potential target for therapeutic intervention to modify vascular pathology. This paper is an overview of matrix metalloproteinases and their role in the pathophysiology, diagnosis and treatment of AAA.

LITERATURE SEARCH

Comprehensive search of the MEDLINE, EMBASE and HEAL-Link databases from 1980 to 2003.

FINDINGS

Increased levels of MMPs expression and activity have been demonstrated within the aortic wall of AAA, associating with histological alterations. An imbalance between MMPs and their inhibitors (Tissue Inhibitors of Matrix Metalloproteinases - TIMPs), may tip the equilibrium towards matrix degradation. MMPs as systemic biochemical markers of AAAs may contribute to diagnosis of unsuspected AAAs or to the surveillance of patients with small AAAs. Evidence of variations in MMPs, TIMPs and their mediator genes promoting the increased inheritance susceptibility of AAAs is less well documented. However,a broad spectrum of pharmaceutical agents (e.g. doxycycline, statins etc.) is known to inhibit MMP activity and attenuate medial destruction.

CONCLUSION

Randomized clinical studies in patients in the early stages of AAA or in healthy individuals with great propensity to AAA development are required to demonstrate the causative relationship between MMPs and AAA. It still remains obscure whether long-term administration of MMP inhibitors can decelerate or even prevent the need for surgical repair.

Clusterin, an abundant serum factor, is a possible negative regulator of MT6-MMP/MMP-25 produced by neutrophils

MT6-MMP/MMP-25 is the latest member of the membrane-type matrix metalloproteinase (MT-MMP) subgroup in the MMP family and is expressed in neutrophils and some brain tumors. The proteolytic activity of MT6-MMP has been studied using recombinant catalytic fragments and shown to degrade several components of the extracellular matrix. However, the activity is possibly modulated further by the C-terminal hemopexin-like domain, because some MMPs are known to interact with other proteins through this domain. To explore the possible function of this domain, we purified a recombinant MT6-MMP with the hemopexin-like domain as a soluble form using a Madin-Darby canine kidney cell line as a producer. Mature and soluble MT6-MMP processed at the furin motif was purified as a 45-kDa protein together with a 46-kDa protein having a single cleavage in the hemopexin-like domain. Interestingly, 73- and 70-kDa proteins were co-purified with the soluble MT6-MMP by forming stable complexes. They were identified as clusterin, a major component of serum, by N-terminal amino acid sequencing. MT1-MMP that also has a hemopexin-like domain did not form a complex with clusterin. MT6-MMP forming a complex with clusterin was detected in human neutrophils as well. The enzyme activity of the soluble MT6-MMP was inactive in the clusterin complex. Purified clusterin was inhibitory against the activity of soluble MT6-MMP. On the other hand, it had no effect on the activities of MMP-2 and soluble MT1-MMP. Because clusterin is an abundant protein in the body fluid in tissues, it may act as a negative regulator of MT6-MMP in vivo.

Proteolytic events of wound-healing--coordinated interactions among matrix metalloproteinases (MMPs), integrins, and extracellular matrix molecules

During wound-healing, cells are required to migrate rapidly into the wound site via a proteolytically generated pathway in the provisional matrix, to produce new extracellular matrix, and, subsequently, to remodel the newly formed tissue matrix during the maturation phase. Two classes of molecules cooperate closely to achieve this goal, namely, the matrix adhesion and signaling receptors, the integrins, and matrix-degrading and -processing enzymes, the matrix metalloproteinases (MMPs). There is now substantial experimental evidence that blocking key molecules of either group will prevent or seriously delay wound-healing. It has been known for some time now that cell adhesion by means of the integrins regulates the expression of MMPs. In addition, certain MMPs can bind to integrins or other receptors on the cell surface involved in enzyme activation, thereby providing a mechanism for localized matrix degradation. By proteolytically modifying the existing matrix molecules, the MMPs can then induce changes in cell behavior and function from a state of rest to migration. During wound repair, the expression of integrins and MMPs is simultaneously up-regulated. This review will focus on those aspects of the extensive knowledge of fibroblast and keratinocyte MMPs and integrins in biological processes that relate to wound-healing.

Shedding of membrane type matrix metalloproteinase 5 by a furin-type convertase: a potential mechanism for down-regulation

The shedding of membrane-associated proteins has been recognized as a regulatory mechanism to either up-regulate or down-regulate cellular functions by releasing membrane-bound growth factors or removing ectodomains of adhesion molecules and receptors. We have reported previously that the ectoenzyme of membrane type matrix metalloproteinase 5 (MT5-MMP) is shed into extracellular milieu (Pei, D. (1999) J. Biol. Chem. 274, 8925-8932). Here we present evidence that MT5-MMP is shed by a furin-type convertase activity in the trans-Golgi network. Among proteinase inhibitors screened, only decanoyl-Arg-Val-Lys-Arg-chloromethylketone, a known inhibitor for furin-type convertases, blocked the shedding of MT5-MMP in a dose-dependent manner. As expected, decanoyl-Arg-Val-Lys-Arg-chloromethylketone also prevented the activation of MT5-MMP, raising the possibility that the observed shedding could be autolytic. However, an active site mutant devoid of any catalytic activity, is also shed efficiently, thus ruling out the autolytic pathway. The shedding cleavage was subsequently mapped to the stem region immediately upstream of the transmembrane domain, where a cryptic furin recognition site, (545)RRKERR, was recognized. Indeed, MT5-MMP and furin are co-localized in the trans-Golgi network and the shed species could be detected inside the cells. Furthermore, deletion mutations removing this cryptic site prevented MT5-MMP from shedding. The resulting mutants express a gain-of-function phenotype by mediating more robust activation of proMMP-2 than the wild type molecule. Thus, shedding provides a potential mechanism to regulate proteolytic activity of membrane-bound MMPs.

Subcellular distribution and cytokine- and chemokine-regulated secretion of leukolysin/MT6-MMP/MMP-25 in neutrophils

Leukolysin, originally isolated from human leukocytes, is the sixth member of the membrane-type matrix metalloproteinase (MT-MMP) subfamily with a potential glycosylphosphatidylinositol (GPI) anchor. To understand its biological functions, we screened subpopulations of leukocytes and localized the expression of leukolysin at the mRNA level to neutrophils. Polyclonal and mono-specific antisera raised against a synthetic peptide from its hinge region recognized a major protein species at 56 kDa and several minor forms between 38 and 45 kDa in neutrophil lysates. In resting neutrophils, leukolysin is distributed among specific granules ( approximately 10%), gelatinase granules ( approximately 40%), secretory vesicles ( approximately 30%), and the plasma membrane ( approximately 20%), a pattern distinct from that of neutrophil MMP-8 and MMP-9. Consistent with its membrane localization and its reported GPI anchor, leukolysin partitions into the detergent phase of Triton X-114 and can be released from intact resting neutrophils by glycosylphosphatidylinositol-specific phospholipase C. Phorbol myristate acetate stimulates neutrophils to discharge 100% of leukolysin from specific and gelatinase granules and approximately 50% from the secretory vesicles and plasma membrane, suggesting that leukolysin can be mobilized by physiological signals to the extracellular milieu as a soluble enzyme. Indeed, interleukin 8, a neutrophil chemoattractant, triggered a release of approximately 85% of cellular leukolysins by a process resistant to a mixture of proteinase inhibitors, including aprotinin, BB-94, pepstatin, and E64. Finally, purified recombinant leukolysin can degrade components of the extracellular matrix. These results not only establish leukolysin as the first neutrophil-specific MT-MMP but also implicate it as a cytokine/chemokine-regulated effector during innate immune responses or tissue injury.

Expression and localization of transcripts of MT5-MMP and its related MMP in the ovary of the medaka fish Oryzias latipes

cDNA clones of MT5-matrix metalloproteinase (MT5-MMP) and a related protein (designated MT5-MMP-del) were isolated by screening the cDNA library and by 3'-rapid amplification of cDNA ends using an ovary RNA of the medaka fish Oryzias latipes. The MT5-MMP clone encodes a protein of 546 amino acids while the MT5-MMP-del clone encodes a protein of 431 amino acids. Compared with mammalian counterparts, the fish MT5-MMP and MT5-MMP-del both lack the signal peptide and a part of the prodomain. The fish MT5-MMP and MT5-MMP-del were different in that the latter did not have the stem/transmembrane/cytoplasmic domain. The two fish MMPs were expressed in the ovary, testis, brain, and intestine. In the ovary, MT5-MMP mRNA was expressed in the oocytes of small growing follicles. In contrast, MT5-MMP-del mRNA was found in the stromal interstitial cells. These results strongly suggest that a MT5-MMP/gelatinase A cascade may possibly operate in the process of spawning and/or other events associated with ovulated oocytes or fertilized eggs of the medaka fish.

MMP-28, a new human matrix metalloproteinase with an unusual cysteine-switch sequence is widely expressed in tumors

We report the discovery, cloning, and characterization of a novel human matrix metalloproteinase (MMP-28) cDNA gene. The deduced 520-amino-acid sequence of MMP-28 includes a signal peptide, a prodomain with an unusual cysteine-switch PRCGVTD motif followed by the furin cleavage RRKKR site, a catalytic domain, a hinge-region and a hemopexin-like domain. On the basis of their structural characteristics, MMP-28 belongs to the MMP-19 subfamily. The genomic MMP-28 gene uniquely mapped to chromosome 17q11.2 includes eight exons and seven introns. The broad range of expression in carcinomas as well as normal adult and fetal tissues suggests an important functional role for MMP-28.

Overexpression of matrix metalloproteinases leads to lethality in transgenicXenopus laevis: Implications for tissue-dependent functions of matrix metalloproteinases during late embryonic development

The extracellular matrix (ECM) functions as the structural support of cells and as a medium for cell-cell interactions. It is understood to play critical roles in development. ECM remodeling is mediated largely through the action of matrix metalloproteinases (MMPs), a family of Zn2+-dependent proteases capable of degrading various proteinaceous components of the ECM. MMPs are expressed in many developmental and pathologic processes. However, few studies have been carried out to investigate the function of MMPs during embryogenesis and postembryonic organogenesis. By using Xenopus development as a model system, we have previously shown that several MMP genes are expressed from neurulation to the completion of embryogenesis in distinct tissues/organs, suggesting that ECM remodeling during mid- to late embryogenesis occurs in an organ-specific manner. By using the recently developed transgenic technology for Xenopus laevis, we overexpressed Xenopus MMPs stromelysin-3 (ST3) and collagenase-4 (Col4) under the control of a ubiquitous promoter and observed that embryos with overexpressed ST3 or Col4, but not the control green fluorescent protein (GFP), died in a dose-dependent manner during late embryogenesis. The specificity of this embryonic lethal phenotype was confirmed by the failure of a catalytically inactive mutant of ST3 to affect development. Finally, overexpression of a mammalian membrane type-MMP also led to late embryonic lethality in Xenopus embryos, suggesting that membrane type-MMPs have functions in vivo for ECM remodeling, in addition to being activators of other pro-MMPs. These data together with the developmental expression of several MMPs during Xenopus development, suggest that MMPs play important roles during mid- to late embryogenesis and that proper regulation of MMP genes is critical for tissue morphogenesis and organogenesis.

CD30 shedding from Karpas 299 lymphoma cells is mediated by TNF-alpha-converting enzyme

CD30 is a costimulatory receptor on activated lymphocytes and a number of human lymphoma cells. Specific ligation of membrane-bound CD30 or cellular stimulation by PMA results in a metalloproteinase-mediated down-regulation of CD30 and release of its soluble ectodomain (sCD30). In this report, it is demonstrated that PMA-induced CD30 cleavage from Karpas 299 cells was mediated by a membrane-anchored metalloproteinase which was active on intact cells following 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate extraction of membrane preparations. Moreover, CD30 shedding was blocked by the synthetic hydroxamic acid-based metalloproteinase inhibitor BB-2116 (IC(50), 230 nM) and the natural tissue inhibitor of metalloproteinases (TIMP)-3 (IC(50), 30 nM), but not by the matrix metalloproteinase inhibitors TIMP-1 and TIMP-2. This inhibition profile is similar to that of the TNF-alpha- converting enzyme (TACE) and, indeed, mRNA transcripts of the membrane-bound metalloproteinase-disintegrin TACE could be detected in Karpas 299 cells. The ectodomain of TACE was expressed in bacteria as a GST fusion protein (GST-TACE) which cleaved CD30 from the surface of Karpas 299 cells and concomitantly increased the level of sCD30 in the cell supernatants. Hence, TACE does not only control the release of TNF-alpha, but also that of sCD30.