Increased Matrix Metalloproteinase Activity Research Articles

Increased Apparent Diffusion Coefficients on MRI Linked with Matrix Metalloproteinases and Edema in White Matter after Bilateral Carotid Artery Occlusion in Rats

White matter (WM) injury after bilateral common carotid artery occlusion (BCAO) in rat is associated with disruption of the blood-brain barrier (BBB) by matrix metalloproteinases (MMPs). We hypothesized that WM injury as seen on magnetic resonance imaging (MRI) would correlate with regions of increased MMP activity. MRI was performed 3 days after BCAO surgery in rats. Apparent diffusion coefficients (ADC) were calculated and vascular permeability was quantified by the multiple-time graphical analysis (MTGA) method, using gadolinium-diethylenetriamine pentaacid (Gd-DTPA). After MRI, one group of animals had BBB permeability measured in the WM with (14)C-sucrose, and another had Evans blue (EB) injected for fluorescent microscopy for MMP-2, MMP-9, tight junction proteins (TJPs), and in situ zymography. We found that ADC values were increased in WM in BCAO rats compared with controls (P<0.05). WM with increased ADC had leakage of EB. MMP-2 and MMP-9 activity on in situ zymograms corresponded with leakage of EB. Although increased permeability to EB could be visualized, permeability quantification with (14)C-sucrose and Gd-DTPA failed to show increases and TJPs were intact. We propose that increased ADC, which is a marker of vasogenic edema, is related to activity of MMP-2 and MMP-9. MRI provides unique information that can be used to guide tissue studies of WM injury.

Letter by Csont and Ferdinandy Regarding Article, “Biglycan Is Required for Adaptive Remodeling After Myocardial Infarction”

To the Editor: We read with great interest the article by Westermann et al1 in which the authors showed that biglycan expression was strongly increased in the myocardium after permanent coronary occlusion in wild-type mice. In the hearts of bgn −/ 0 mice 21 days after coronary occlusion, however, collagen matrix organization was impaired, and several parameters of left ventricular function were deteriorated. Furthermore, these animals showed increased mortality rates after infarction. The authors conclude that the complete absence of biglycan is deleterious and prevents the establishment of a stable infarct scar and hemodynamic adaptation, suggesting that biglycan is required for proper infarct healing. Although the observations of the authors are most valuable, the major conclusion of the authors1 is …

Regulation of vascular smooth muscle cell expression and function of matrix metalloproteinases is mediated by estrogen and progesterone exposure

Postmenopausal women receiving hormone replacement therapy (HRT) have been reported to have more adverse outcomes after vascular reconstructions, including increased intimal hyperplasia development and bypass graft failure. HRT may be affecting the pathway contributing to intimal hyperplasia. An important component of this pathway involves matrix metalloproteinases (MMPs), implicated in vascular remodeling due to their ability to degrade components of the extracellular matrix. We hypothesize that estrogen (Est) and progesterone (Prog) upregulate the MMP pathway in vascular smooth muscle cells (VSMCs) thereby increasing MMP activity and function. VSMCs were incubated with Est (5 ng/mL), Prog (50 ng/mL), Est + Prog combination (Est/Prog), and/or doxycycline (40 microg/mL; Doxy). Using reverse transcriptase polymerase chain reaction (RT-PCR) analysis we have previously shown membrane type 1-MMP (MT1-MMP) messenger ribonucleic acid (mRNA) levels are significantly increased by Est. Here, Western blot analyses indicated MT1-MMP and MMP-2 protein levels, not tissue inhibitor of MMP-2 (TIMP-2), were increased in response to Est and Est/Prog (P < .05 vs control). In-gel zymography revealed that Est and Est/Prog resulted in increased MMP-2 activity (hormone groups, P < .05 vs control) with no significant difference among the hormone groups. VSMC migration was increased by 45 +/- 14% in response to Est (P < .05 vs control), as measured using a modified Boyden chamber assay. Doxycycline significantly inhibited basal and Est/Prog-stimulated increases in MMP-2 activity (P < .05 vs control; P < .05 vs hormone groups), and partially blocked basal and hormonally stimulated migration (P < .05 vs control and Est). Estrogen and progesterone affects the MMP pathway by increasing MMP-2 enzymatic activity, possibly via the upregulation of MT1-MMP expression without a corresponding increase in TIMP expression. This increased collagenase activity increases VSMC motility and their ability to migrate through a collagen type IV lattice. Est/Prog upregulation of MT1-MMP may contribute to the adverse effect of HRT on vascular interventions.

Matrix Metalloproteinase Inhibition Attenuates Atrial Remodeling and Vulnerability to Atrial Fibrillation in a Canine Model of Heart Failure

Background Atrial structural remodeling occurs in evolving heart failure (HF) and is an important substrate for the development of atrial fibrillation (AF). The matrix metalloproteinases (MMPs) play a role in extracellular remodeling, and recent studies have demonstrated increased atrial MMP activity in HF. Whether increased MMP activity directly contributes to atrial remodeling and AF in the setting of HF remains unclear. The current study examined the effects of MMP inhibition on atrial structural remodeling and AF vulnerability during HF progression. Methods and Results Three groups of dogs (n = 5 each)—control normal dogs (controls) and 10 dogs subjected to simultaneous atrioventricular pacing (SAVP) for 2 weeks to induce HF and randomly assigned to treatment with placebo (SAVP-placebo) or a MMP inhibitor PGE-7113313, a MMP-1-sparing MMP inhibitor, 6 mg/kg orally twice daily (SAVP-MMPi)—were studied. SAVP-MMPi dogs had less AF inducibility (percent of burst attempts leading to AF episodes: 1.7 ± 2.9 seconds vs. 23±19 seconds, mean ± SD, P < .05) and maintenance (AF duration: 253 [105 to 326] vs. 1932 [1296 to 2724] seconds, median [25th-75th quartile], P < .05) than SAVP-placebo dogs. The SAVP-MMPi dogs had significantly smaller increases in atrial myocyte cross sectional area, collagen area fraction, and MMP-9 activity relative to controls than SAVP-placebo. There were, however, no significant differences in the changes in chamber dimension and function in the left atrium. Conclusions This unique finding of an attenuation of the vulnerability to AF in conjunction with reduced myocyte hypertrophy and fibrosis after MMP inhibition suggests that heightened MMP activity in the atria contributes to atrial structural remodeling and AF promotion during evolving HF.

Sodium hydrogen exchanger and phospholipase D are required for α 1-adrenergic receptor stimulation of metalloproteinase-9 and cellular invasion in CCL39 fibroblasts

Matrix metalloproteinase 9 (MMP-9) plays a critical role in digesting the extracellular matrix and has a vital function in tumor metastasis and invasion; this protease activity is significantly increased in non-small cell lung cancers. The sodium hydrogen exchanger isoform 1 (NHE1) functions as a focal point for signal coordination and cytoskeletal reorganization. NHE1 is thought to play a central role in establishing signaling components at the leading edge of a migrating cell. Therefore, we studied the relationship between NHE1 and MMP-9 activity in Chinese hamster lung fibroblasts (CCL39) stimulated with phenylephrine (PE). We show that PE increases MMP-9 gelatinolytic activity in CCL39 cells. The inhibition of phospholipase D (PLD) signaling abrogated PE-induced MMP-9 activity. The role of PLD as an essential signaling intermediate was confirmed when the addition of permeable phosphatidic acid increased MMP-9 activity in the same cells. PE-induced invasion was increased 1.9-fold over controls and the PE response was lost when 1-butanol was used to block PLD signaling. Cells pre-treated with the NHE1 inhibitor, 5-( N-ethyl- N-isopropyl) amiloride (EIPA) prior to PE addition resulted in a notable decrease in MMP-9 activation and cell invasion as compared to untreated PE-stimulated cells. CCL39 NHE1 null cells demonstrated no increase in MMP-9 protease activity or cell invasion in response to PE treatment. Reconstitution of NHE1 expression recovered the PE-induced activation of protease activity and cell invasion. MMP-9 processing was altered in cells expressing a proton transport defective NHE1 but retained the ability to respond to PE. Conversely, cells expressing an ezrin, radixin, moesin (ERM)-binding deficient NHE1 had a lower MMP-9 activity and the protease did not respond to PE addition. Parallel studies on NCI-H358 non-small cell lung cancer (NSCL) cells showed that PE stimulated both MMP-9 activity and cell invasion in an NHE1 dependent manner. This work describes for the first time a PE-induced relationship between NHE1 and MMP-9 and a new potential mechanism by which NHE1 could promote tumor formation and metastasis.

The migration of human lens epithelial cells induced by UV-irradiation in vitro

Objective Ultraviolet (UV) radiation is one of the important cataract risk factors. However, the pathogenesis is still poorly understood. The migration of human lens epithelial cells(HLECs) plays a crucial role in the remodeling of lens capsule and cataract formation. The purpose of this study is to investigate the mechanism of UV inducing cataractogenesis. Methods The toxicity of UV-irradiation on HLECs was assessed by Methyl thiazolyl tetrazolium(MTT) assay. The activity of matrix metalloproteinase-2(MMP-2) was observed by Gelatin zymography. The migration of HLECs was examined by Cell Track Motility. Results UV-irradiation does great harm to HLECs, and may induce apoptosis in the cells when UV higher than 15 mj/cm 2. UV significantly increased MMP-2 activity in a time-dependent manner. In addition, the irradiation could induce the migration of HLECs. Conclusion UV-irradiation could induce the migration of HLECs by increasing the activity of MMP-2.

Human C-reactive protein promotes oxidized low density lipoprotein uptake and matrix metalloproteinase-9 release in Wistar rats

C-reactive protein (CRP) is present in the atherosclerotic plaques and appears to promote atherogenesis. Intraplaque CRP colocalizes with oxidized low density lipoprotein (OxLDL) and macrophages in human atherosclerotic lesions. Matrix metalloproteinase-9 (MMP-9) has been implicated in plaque rupture. CRP promotes OxLDL uptake and MMP induction in vitro; however, these have not been investigated in vivo. We examined the effect of CRP on OxLDL uptake and MMP-9 production in vivo in Wistar rats. CRP significantly increased OxLDL uptake in the peritoneal and sterile pouch macrophages compared with human serum albumin (huSA). CRP also significantly increased intracellular cholesteryl ester accumulation compared with huSA. The increased uptake of OxLDL by CRP was inhibited by pretreatment with antibodies to CD32, CD64, CD36, and fucoidin, suggesting uptake by both scavenger receptors and Fc-gamma receptors. Furthermore, CRP treatment increased MMP-9 activity in macrophages compared with huSA, which was abrogated by inhibitors to p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), and nuclear factor (NF)-kappaB but not Jun N-terminal kinase (JNK) before human CRP treatment. Because OxLDL uptake by macrophages contributes to foam cell formation and MMP release contributes to plaque instability, this study provides novel in vivo evidence for the role of CRP in atherosclerosis.

Inhibition of matrix metalloproteinases prevents peroxynitrite‐induced contractile dysfunction in the isolated cardiac myocyte

The potent oxidant peroxynitrite (ONOO(-)) induces mechanical dysfunction in the intact heart in part through activation of matrix metalloproteinase-2 (MMP-2). This effect may be independent of the proteolytic actions of MMPs on extracellular matrix proteins. The purpose of this study was to examine the effects of ONOO(-) on contractile function at the level of the single cardiac myocyte and whether this includes the action of MMPs. Freshly isolated ventricular myocytes from adult rats were superfused with Krebs-Henseleit buffer at 21 degrees C and paced at 0.5 Hz. Contractility was measured using a video edge-detector. ONOO(-) or decomposed ONOO(-) (vehicle control) were co-infused over 40 min to evaluate the contraction cease time (CCT). The effects of ONOO(-) on intracellular [Ca(2+)] were determined in myocytes loaded with calcium green-1 AM. MMP-2 activity was measured by gelatin zymography. ONOO(-) (30-600 microM) caused a concentration-dependent reduction in CCT. Myocytes subjected to 300 microM ONOO(-) had a shorter CCT than decomposed ONOO(-) (14.9+1.5 vs 32.2+3.5 min, n=7-8; P<0.05) and showed increased MMP-2 activity. The MMP inhibitors doxycycline (100 microM) or PD 166793 (2 microM) reduced the decline in CCT induced by 300 microM ONOO(-). ONOO(-) caused shorter calcium transient cease time and significant alterations in intracellular [Ca(2+)] homoeostasis which were partially prevented by doxycycline. This is the first demonstration that inhibition of MMPs protects the cardiac myocyte from ONOO(-)-induced contractile failure via an action unrelated to proteolysis of extracellular matrix proteins.

Matrix Metalloproteinase-9 Is Involved in the Development and Plasticity of Retinotectal Projections in Rats

Objective: During postnatal development, retinotectal projections undergo a process of misplaced axon elimination, leading to a topographical matching between the retinal surface and the superior colliculus. Matrix metalloproteinases (MMPs) have been implicated in the development and plasticity of the nervous system. We studied the expression and role of MMPs during normal development of retinotectal projections and after monocular enucleation-induced plasticity. Material and Methods: Lister hooded rats at different postnatal ages received subpial ethylene vinyl acetate 40W implants to deliver an MMP inhibitor or vehicle to the superior colliculus. Animals received intraocular injections of horseradish peroxidase for anterograde tracing of ipsilateral projections. For immunoblotting and zymography, colliculi were removed without fixation. Results: We observed the highest MMP activity in the first postnatal week, with decreasing activity thereafter. Monocular enucleation at postnatal day 10 yielded a rapid increase in MMP activity, 24 h following denervation of the contralateral colliculus. Importantly, inhibition of MMP activity in vivo induced a marked delay of axonal clustering along the medial aspect of colliculus. Conclusions: Our data indicate that MMPs are crucial in retinotectal development concurring to the fine tuning of topographical order and synaptic specificity of these connections.

Inhibition of integrative repair of the meniscus following acute exposure to interleukin‐1 in vitro

Damage or loss of the meniscus is associated with progressive osteoarthritic degeneration of the knee joint. Injured and degenerative joints are characterized by elevated levels of the pro-inflammatory cytokine interleukin-1 (IL-1), which with prolonged exposure can induce catabolic and anti-anabolic activities that inhibit tissue repair. We used an in vitro model system to examine the hypotheses that acute exposure to IL-1 inhibits meniscal repair, and that an IL-1-mediated increase in matrix metalloproteinase (MMP) activity is associated with the inhibition of repair. Integrative tissue repair was studied between concentric explants of porcine medial menisci that were treated with IL-1alpha acutely (100 pg/mL for 1 or 3 days) or chronically (100 pg/mL for entire culture duration). After 14 and 28 days in culture, biomechanical testing, cell viability, and histology were performed to assess meniscal repair. Total specific MMP activity in the culture media was measured using a quenched fluorescent substrate. As little as 1 day of IL-1 exposure significantly reduced shear strength, cell accumulation, and tissue repair compared to controls. IL-1 exposure for 1 or 3 days significantly increased MMP activity that subsided by day 9. With chronic IL-1 exposure, MMP activity remained elevated for the duration of culture and was negatively correlated with repair strength. Our study shows that short-term exposure to physiologically relevant concentrations of IL-1 significantly reduces meniscal repair in vitro, and thus may potentially inhibit the intrinsic repair response in vivo. The suppression of IL-1 or MMP expression and/or activity warrant investigation as potential strategies for promoting meniscal repair.

Matrix metalloproteinase‐2 expression and promoter/enhancer activity in skeletal muscle atrophy

Matrix metalloproteinase-2 (MMP-2) appears to be the dominant MMP activated during skeletal muscle atrophy. However, little is known about cell-specific regulatory mechanisms of MMP-2 transcription in vivo. In this study, we used a mouse model of muscle atrophy induced by complete Achilles tendon transection. Time-dependent muscle weight loss, nuclei density reduction, and extracellular matrix degeneration were observed consistently after Achilles tendon transection. Increased MMP-2 expression was confirmed at the mRNA and protein level. Experiments using transgenic mice with a MMP-2 promoter/enhancer reporter construct demonstrated markedly increased MMP-2 promoter/enhancer activity in atrophic skeletal muscle. Tissue-specific upregulation of MMP-2 promoter activity was observed not only in myocytes, but also in blood vessels, nerve, and fascia. The transcription factors c-Jun and FosB were expressed at high levels in atrophic muscle, suggesting a role in MMP-2 upregulation. These findings show that increased MMP-2 activity in disused atrophic muscle and supporting tissues is regulated, at least in part, by increased MMP-2 promoter/enhancer activity.

A neurokinin‐1 receptor antagonist that reduces intraabdominal adhesion formation increases peritoneal matrix metalloproteinase activity

Adhesions remain a significant complication of abdominal surgery. There is a growing body of evidence suggesting that remodeling of peritoneal extracellular matrix by matrix metalloproteinases (MMPs) is involved in adhesion formation. We have shown that administration of a specific neurokinin-1 receptor (NK-1R) antagonist (CJ-12,255, Pfizer) to rats within 5 hours of surgery reduces intraabdominal adhesion formation. Because substance P (SP), the primary NK-1R ligand, is known to augment tissue fibrosis, the aim of this study was to determine the effects of NK-1R antagonist administration on peritoneal MMP expression and activity 24 hours after surgery in a rat adhesion model. Following laparotomy, four ischemic buttons were created on the peritoneum of rats that received either an intraperitoneal NK-1R antagonist or a vehicle at surgery. Adhesion formation was assessed 7 days later. Peritoneal fluid and tissue were collected at 24 hours to assess total MMP activity, as well as MMP-2, MMP-8, and MMP-9 activity. Specific MMP and tissue inhibitors of MMP mRNAs were measured, and the effects of SP on MMP-3 expression were determined in Met-5A cells, a human peritoneal mesothelial cell line. NK-1R antagonist administration reduced adhesion formation by 47% (p<0.05) at 7 days and significantly increased the total MMP activity in peritoneal fluid at 24 hours. There was an accompanying increase (p<0.05) in MMP-8 and MMP-9 mRNA expression and activity in peritoneal tissue and fluid, respectively. MMP-3 mRNA was also increased in the 24-hour peritoneal tissue, and exposure of Met-5A cells to SP reduced MMP-3 expression and activity. These data support a role for MMPs, specifically MMP-3, MMP-8, and MMP-9, in intraabdominal adhesion formation and suggest that the NK-1R antagonist may reduce adhesions, in part, by increasing MMP activity in the peritoneum by 24 hours after surgery.

Matrix metalloproteinase-9, a potential biological marker in invasive pituitary adenomas

We analyzed MMP-9 expression using mRNA and protein level determinations and explored the possibility that matrix metalloproteinase-9 (MMP-9) is a potential biological marker of pituitary adenoma invasiveness and whether MMP-9 could be used to discriminate the extent of invasiveness among different hormonal subtypes, tumor sizes, growth characteristics, and primary versus recurrent tumors. 73 pituitary tumor specimens were snap frozen in liquid nitrogen immediately after surgical resection. RNA and protein were extracted. MMP-9 mRNA transcripts were analyzed by quantitative RT-PCR. MMP-9 protein activity was analyzed by gelatin zymography and validated by western blot analysis. Immunohistochemistry was performed to identify the presence and localization of MMP-9 in pituitary adenomas. Statistical differences between results were determined using Student's t-test or one way ANOVA. Comparing different hormonal subtypes of noninvasive and invasive pituitary tumors, MMP-9 mRNA expression was significantly increased in the majority of invasive adenomas. Considering the protein levels, our data also showed a significant increase in MMP-9 activity in the majority of invasive adenomas and these differences were confirmed by western blot analysis and immunohistochemistry. In addition, consistent differences in MMP-9 expression levels were found according to tumor subtype, tumor size, tumor extension and primary versus redo-surgery. MMP-9 expression can consistently distinguish invasive pituitary tumors from noninvasive pituitary tumors and would reflect the extent of invasiveness in pituitary tumors according to tumor subtype, size, tumor extension, primary and redo surgery, even at early stages of invasiveness. MMP-9 may be considered a potential biomarker to determine and predict the invasive nature of pituitary tumors.

Cytokines regulate matrix metalloproteinases and migration in cardiac fibroblasts

We sought to define the relationship between cytokine stimulated release of matrix metalloproteinases (MMPs) and cell migration using adult rat cardiac fibroblasts. Interleukin-1β (IL-1β) increased release of MMP-2, -3, and -9, and TIMP-1, by 3–6-fold, measured by immunoblotting and gel zymography. Tumor necrosis factor-α (TNFα) augmented IL-1β stimulated release of MMP-9, but not MMP-2 or -3. Transforming growth factor-β1 (TGFβ1) attenuated all the responses to IL-1β. IL-1β was also the most robust stimulus of adult rat cardiac fibroblast migration, measured in Boyden chamber assays. The combination of IL-1β plus TNFα substantially enhanced migration, whereas TGFβ1 strongly inhibited the migratory response to IL-1β. The pan-selective MMP inhibitor GM 6001 effectively blocked IL-1β stimulated migration. Pharmacologic inhibitors selective for ERK, JNK, and p38 MAP kinase pathways inhibited the IL-1β regulation of individual MMPs. Increased MMP activity associated with migration of cardiac fibroblasts may be important determinants of cytokine-directed remodeling of injured myocardium.

Epigenetic silencing of claudin‐6 promotes anchorage‐independent growth of breast carcinoma cells

Cancer cells often exhibit loss of functional tight junctions (TJ), and disruption of the TJ structure is associated with cancer development. However, whether loss of a certain type of claudin, an integral membrane protein of TJ, is involved in malignant phenotypes remains to be clarified. Based on a report that claudin-6 functions as a tumor suppressor for breast cancer, the authors show here that suppression of claudin-6 expression results in increased resistance to various apoptogens, and causally enhances anchorage-independent growth properties. Because claudin-6 expression is partially silenced by promoter CpG island hypermethylation in MCF7 breast carcinoma cells, a synergistic effect of a demethylator and histone deacetylase inhibitor up-regulates the expression of endogenous claudin-6, which is sufficient for apoptotic sensitization and abrogation of colony-forming efficacy. In addition, decreased expression of claudin-6 promotes cellular invasiveness and transendothelial migration, accompanied by an increase in matrix metalloproteinase activity. These data suggest that the methylator phenotype of claudin-6 may at least partially contribute to enhanced tumorigenic and invasive properties of breast carcinoma cells.

Evidence for differential changes of junctional complex proteins in murine neurocysticercosis dependent upon CNS vasculature

The delicate balance required to maintain homeostasis of the central nervous system (CNS) is controlled by the blood–brain barrier (BBB). Upon injury, the BBB is disrupted compromising the CNS. BBB disruption has been represented as a uniform event. However, our group has shown in a murine model of neurocysticercosis (NCC) that BBB disruption varies depending upon the anatomical site/vascular bed analyzed. In this study further understanding of the mechanisms of BBB disruption was explored in blood vessels located in leptomeninges (pial vessels) and brain parenchyma (parenchymal vessels) by examining the expression of junctional complex proteins in murine brain infected with Mesocestoides corti. Both pial and parenchymal vessels from mock infected animals showed significant colocalization of junctional proteins and displayed an organized architecture. Upon infection, the patterned organization was disrupted and in some cases, particular tight junction and adherens junction proteins were undetectable or appeared to be undergoing proteolysis. The extent and timing of these changes differed between both types of vessels (pial vessel disruption within days versus weeks for parenchymal vessels). To approach potential mechanisms, the expression and activity of matrix metalloproteinase-9 (MMP-9) were evaluated by in situ zymography. The results indicated an increase in MMP-9 activity at sites of BBB disruption exhibiting leukocyte infiltration. Moreover, the timing of MMP activity in pial and parenchymal vessels correlated with the timing of permeability disruption. Thus, breakdown of the BBB is a mutable process despite the similar structure of the junctional complex between pial and parenchymal vessels and involvement of MMP activity.

ERM/ETV5 Up-regulation Plays a Role during Myometrial Infiltration through Matrix Metalloproteinase-2 Activation in Endometrial Cancer

We have described recently the Ets family transcription factor, ERM/ETV5, specifically up-regulated in endometrioid endometrial carcinoma (EEC) and associated with myometrial infiltration. Ets family members have been correlated to tumor progression by up-regulating the expression of matrix-degrading proteases. In the present study, we investigated the possibility that in EEC, ERM/ETV5 may act by inducing the expression of genes involved in extracellular matrix remodeling. Unraveling the molecular events associated with the initiation of tumor invasion would represent an obvious improvement for EEC patients. The overexpression of ERM/ETV5 induced scattering in the endometrial cancer cell line Hec-1A, correlating to increased matrix metalloproteinase-2 (MMP-2) gelatinase activity. Both chromatin immunoprecipitation and reversion experiments with RNA interference and specific MMP-2 inhibitor showed a functional link between ERM/ETV5 overexpression and MMP-2 activation. The increased MMP-2 activity associated with overexpressed ERM/ETV5 in a mouse model conferred invasive capacity to endometrial tumors. Orthotopically implanted overexpressing ERM/ETV5 tumors presented a more aggressive and infiltrative pattern of myometrial invasion. Finally, the specific localization of ERM/ETV5 and MMP-2 at the invasive front of myometrial infiltrating human endometrial carcinomas further reinforced the hypothesis of a role for ERM/ETV5 in the early steps of endometrial dissemination. Taken together, these results lead us to propose that in EEC, ERM/ETV5 acts through MMP-2 gelatinolytic activity to confer invasive capabilities, associated with an initial switch to myometrial infiltration. They also postulate ERM/ETV5 as a valuable marker for patient stratification and a transcription pathway that should be evaluated for therapies specifically targeting the initial steps of EEC dissemination.

β-Dystroglycan as a Target for MMP-9, in Response to Enhanced Neuronal Activity

Matrix metalloproteinase-9 has recently emerged as an important molecule in control of extracellular proteolysis in the synaptic plasticity. However, no synaptic targets for its enzymatic activity had been identified before. In this report, we show that beta-dystroglycan comprises such a neuronal activity-driven target for matrix metalloproteinase-9. This notion is based on the following observations. (i) Recombinant, autoactivating matrix metalloproteinase-9 produces limited proteolytic cleavage of beta-dystroglycan. (ii) In neuronal cultures, beta-dystroglycan proteolysis occurs in response to stimulation with either glutamate or bicuculline and is blocked by tissue inhibitor of metalloproteinases-1, a metalloproteinase inhibitor. (iii) Beta-dystroglycan degradation is also observed in the hippocampus in vivo in response to seizures but not in the matrix metalloproteinase-9 knock-out mice. (iv) Beta-dystroglycan cleavage correlates in time with increased matrix metalloproteinase-9 activity. (v) Finally, beta-dystroglycan and matrix metalloproteinase-9 colocalize in postsynaptic elements in the hippocampus. In conclusion, our data identify the beta-dystroglycan as a first matrix metalloproteinase-9 substrate digested in response to enhanced synaptic activity. This demonstration may help to understand the possible role of both proteins in neuronal functions, especially in synaptic plasticity, learning, and memory.

Molecular characterization of post-thrombotic syndrome

The post-thrombotic syndrome represents a poorly understood and significant vascular health problem. This review focuses on our current understanding of the pathogenesis of post-thrombotic syndrome. We emphasize the cellular and molecular mechanisms that are responsible for the critical components of post-thrombotic syndrome. These include the initiation of deep venous thrombosis, the pathogenesis of elevated venous pressure, and the factors responsible for nonhealing of venous stasis ulcers.

Preconditioning with Chronic Cerebral Hypoperfusion Reduces a Focal Cerebral Ischemic Injury and Increases Apurinic/Apyrimidinic Endonuclease/Redox Factor-1 and Matrix Metalloproteinase-2 Expression

Atherosclerosis may cause severe stenosis of the arteries supplying the brain, which induces chronic cerebral hypoperfusion. Although an infarction often occurs in the chronically hypoperfused brain area, it has been uncertain whether the stroke severity is attenuated or increased when further decrease of blood flow occurs. To test the hypothesis that chronic cerebral hypoperfusion is protective against the subsequent severe ischemia, we examined the effect of chronic cerebral hypoperfusion on brains subjected to acute focal ischemia. Spontaneous hypertensive rats were subjected to middle cerebral artery occlusion/reperfusion four weeks after bilateral common carotid artery ligation (BCAL) or sham operation. The rats with BCAL had smaller infarctions, determined by 2,3,5-triphenyltetrazolium hydrochloride staining, and less severe neurologic deficits than those with sham operation. The number of DNA-damaged cells, examined by the in situ nick translation study, was significantly reduced in animals with BCAL. Immunoreactivity for apurinic/apyrimidinic endonuclease/redox factor-1, which plays a role in cellular defense mechanism, was markedly increased in those with BCAL. Indirect evidence of extracellular matrix remodeling, which might be associated with adaptive arteriogenesis or angiogenesis, was obtained in the form of increased matrix metalloproteinase-2 activity in them. These findings provide experimental evidence that chronic cerebral hypoperfusion would be protective against subsequent severe ischemic insults.