Redox-dependent matrix metalloproteinase-1 expression is regulated by JNK through Ets and AP-1 promoter motifs

Chemotherapy as a regulator of extracellular matrix-cell communication: Implications in therapy resistance

The development of most solid cancers, including pancreatic, breast, lung, liver, and ovarian cancer, involves a desmoplastic reaction: a process of major remodeling of the extracellular matrix (ECM) affecting the ECM composition, mechanics, and microarchitecture. These properties of the ECM influence key cancer cell functions, including treatment resistance. Furthermore, emerging data show that various chemotherapeutic treatments lead to alterations in ECM features and ECM-cell communication. Here, we summarize the current knowledge around the effects of chemotherapy on both the ECM remodeling and ECM-cell signaling and discuss the implications of these alterations on distinct mechanisms of chemoresistance. Additionally, we provide an overview of current therapeutic strategies and ongoing clinical trials utilizing anti-cancer drugs to target the ECM-cell communication and explore the future challenges of these strategies.

Molecular mechanisms of Marine-Derived Natural Compounds as photoprotective strategies

Excessive exposure of the skin to ultraviolet radiation (UVR) causes oxidative stress, inflammation, immunosuppression, apoptosis, and changes in the extracellular matrix, which lead to the development of photoaging and photodamage of skin. At the molecular level, these pathological changes are mainly caused by the activation of related protein kinases and downstream transcription pathways, the increase of matrix metalloproteinase, the formation of reactive oxygen species, and the combined action of cytokines and inflammatory mediators. At present, the photostability, toxicity, and damage to marine ecosystems of most sun protection products in the market have affected their efficacy and safety. Another way is to use natural products produced by various marine species. Marine organisms have evolved a variety of molecular strategies to protect themselves from the harmful effects of ultraviolet radiation, and their unique chemicals have attracted more and more attention in the research of photoprotection and photoaging resistance. This article provides an extensive description of the recent literature on the potential of Marine-Derived Natural Compounds (MDNCs) as photoprotective and photoprotective agents. It reviews the positive effects of MDNCs in counteracting UV-induced oxidative stress, inflammation, DNA damage, apoptosis, immunosuppression, and extracellular matrix degradation. Some MDNCs have the potential to develop feasible solutions for related phenomena, such as photoaging and photodamage caused by UVR.

SOD2, a Potential Transcriptional Target Underpinning CD44-Promoted Breast Cancer Progression

CD44, a cell-adhesion molecule has a dual role in tumor growth and progression; it acts as a tumor suppressor as well as a tumor promoter. In our previous work, we developed a tetracycline-off regulated expression of CD44's gene in the breast cancer (BC) cell line MCF-7 (B5 clone). Using cDNA oligo gene expression microarray, we identified SOD2 (superoxide dismutase 2) as a potential CD44-downstream transcriptional target involved in BC metastasis. SOD2 gene belongs to the family of iron/manganese superoxide dismutase family and encodes a mitochondrial protein. SOD2 plays a role in cell proliferation and cell invasion via activation of different signaling pathways regulating angiogenic abilities of breast tumor cells. This review will focus on the findings supporting the underlying mechanisms associated with the oncogenic potential of SOD2 in the onset and progression of cancer, especially in BC and the potential clinical relevance of its various inhibitors.

Nano-Curcumin Protects Against Sodium Nitrite-Induced Lung Hypoxia Through Modulation of Mitogen-Activated Protein Kinases/c-Jun NH2-Terminal Kinase Signaling Pathway

Background and objective

This study was designed to compare the efficacy of curcumin (CRN) with that of nano-curcumin (N-CRN) in the mitigation of various biochemical indices in hypoxic lung induced by sodium nitrite (SN) in rats.

Methods

Twenty-four adult male albino rats were divided into 4 groups. Group 1: control group received carboxy methyl cellulose; Group 2: hypoxic group injected with single dose of SN (60 mg/kg, s.c.); Group 3: SN-intoxicated rats pre-injected with CRN (100 mg/kg, i.p.); and Group 4: SN-intoxicated rats pre-injected with N-CRN (100 mg/kg, i.p.). Curcumin and N-CRN were administered intraperitoneally 2 hour prior to SN intoxication. Hemoglobin concentration, serum tumor necrosis factor-alpha (TNF-α), and caspase-3 were analyzed. Gene expression of hypoxia inducible factor-1 (HIF-1α), matrix metallo-proteinases (MMP)-2, and tissue inhibitors of metalloproteinases (TIMPs)-2, as well as the protein expression of mitogen-activated protein kinases (MAPKs) and c-Jun NH2-terminal kinase (JNK) were examined in lung tissues.

Results

Hemoglobin level was markedly reduced, and serum TNF-α and caspase-3 were significantly elevated post SN intoxication. The lung MMP-2 and HIF-1α mRNA were overexpressed in the hypoxic group; while TIMP-2 mRNA was downregulated. Sodium nitrite administration increased proteins’ expressions of MAPK and JNK. Pretreatment with CRN or N-CRN markedly mitigated those alterations. These results were supported by histopathological examinations of lung tissue.

Conclusion

Interestingly, N-CRN exhibited a pronounced protective effect via suppression of inflammatory and apoptotic biomarkers and modulation of MAPK/JNK signaling pathway.

The role of redox system in metastasis formation

The metastatic cancer disease represents the real and urgent clinical need in oncology. Therefore, an understanding of the complex molecular mechanisms sustaining the metastatic cascade is critical to advance cancer therapies. Recent studies highlight how redox signaling influences the behavior of metastatic cancer cells, contributes to their travel in bloodstream from the primary tumor to the distant organs and conditions the progression of the micrometastases or their dormant state. Radical oxygen species not only regulate intracellular processes but participate to paracrine circuits by diffusion to nearby cells, thus assuming unpredicted roles in the communication between metastatic cancer cells, blood circulating cells, and stroma cells at site of colonization. Here, we review recent insights in the role of radical oxygen species in the metastasis formation with a special focus on extravasation at metastatic sites.

Oxidative Stress in Pulmonary Fibrosis

Oxidative stress has been linked to various disease states as well as physiological aging. The lungs are uniquely exposed to a highly oxidizing environment and have evolved several mechanisms to attenuate oxidative stress. Idiopathic pulmonary fibrosis (IPF) is a progressive age-related disorder that leads to architectural remodeling, impaired gas exchange, respiratory failure, and death. In this article, we discuss cellular sources of oxidant production, and antioxidant defenses, both enzymatic and nonenzymatic. We outline the current understanding of the pathogenesis of IPF and how oxidative stress contributes to fibrosis. Further, we link oxidative stress to the biology of aging that involves DNA damage responses, loss of proteostasis, and mitochondrial dysfunction. We discuss the recent findings on the role of reactive oxygen species (ROS) in specific fibrotic processes such as macrophage polarization and immunosenescence, alveolar epithelial cell apoptosis and senescence, myofibroblast differentiation and senescence, and alterations in the acellular extracellular matrix. Finally, we provide an overview of the current preclinical studies and clinical trials targeting oxidative stress in fibrosis and potential new strategies for future therapeutic interventions. © 2020 American Physiological Society. Compr Physiol 10:509-547, 2020.

Loss of epitranscriptomic control of selenocysteine utilization engages senescence and mitochondrial reprogramming☆

Critically important to the maintenance of the glutathione (GSH) redox cycle are the activities of many selenocysteine-containing GSH metabolizing enzymes whose translation is controlled by the epitranscriptomic writer alkylation repair homolog 8 (ALKBH8). ALKBH8 is a tRNA methyltransferase that methylates the wobble uridine of specific tRNAs to regulate the synthesis of selenoproteins. Here we demonstrate that a deficiency in the writer ALKBH8 (Alkbh8^def), alters selenoprotein levels and engages senescence, regulates stress response genes and promotes mitochondrial reprogramming. Alkbh8^def mouse embryonic fibroblasts (MEFs) increase many hallmarks of senescence, including senescence associated β-galactosidase, heterocromatic foci, the cyclin dependent kinase inhibitor p16^Ink4a, markers of mitochondrial dynamics as well as the senescence associated secretory phenotype (SASP). Alkbh8^def cells also acquire a stress resistance phenotype that is accompanied by an increase in a number redox-modifying transcripts. In addition, Alkbh8^def MEFs undergo a metabolic shift that is highlighted by a striking increase in the level of uncoupling protein 2 (UCP2) which enhances oxygen consumption and promotes a reliance on glycolytic metabolism. Finally, we have shown that the Alkbh8 deficiency can be exploited and corresponding MEFs are killed by glycolytic inhibition. Our work demonstrates that defects in an epitransciptomic writer promote senescence and mitochondrial reprogramming and unveils a novel adaptive mechanism for coping with defects in selenocysteine utilization.

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Deficiencies in selenocysteine utilization engages cellular senescence and the senescence associated secretory phenotype.

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Alkbh8 deficiency promotes mitochondrial elongation, increased oxygen consumption and a reliance on glycolytic metabolism.

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Cellular adaptions to Alkbh8 deficiency confer stress resistance.

Cysteine Glutathionylation Acts as a Redox Switch in Endothelial Cells

Oxidative post-translational modifications (oxPTM) of receptors, enzymes, ion channels and transcription factors play an important role in cell signaling. oxPTMs are a key way in which oxidative stress can influence cell behavior during diverse pathological settings such as cardiovascular diseases (CVD), cancer, neurodegeneration and inflammatory response. In addition, changes in oxPTM are likely to be ways in which low level reactive oxygen and nitrogen species (RONS) may contribute to redox signaling, exerting changes in physiological responses including angiogenesis, cardiac remodeling and embryogenesis. Among oxPTM, S-glutathionylation of reactive cysteines emerges as an important regulator of vascular homeostasis by modulating endothelial cell (EC) responses to their local redox environment. This review summarizes the latest findings of S-glutathionylated proteins in major EC pathways, and the functional consequences on vascular pathophysiology. This review highlights the diversity of molecules affected by S-glutathionylation, and the complex consequences on EC function, thereby demonstrating an intricate dual role of RONS-induced S-glutathionylation in maintaining vascular homeostasis and participating in various pathological processes.

The peroxidase PRDX1 inhibits the activated phenotype in mammary fibroblasts through regulating c-Jun N-terminal kinases

Background

Reactive oxygen species (ROS), including hydrogen peroxide, drive differentiation of normal fibroblasts into activated fibroblasts, which can generate high amounts of hydrogen peroxide themselves, thereby increasing oxidative stress in the microenvironment. This way, activated fibroblasts can transition into cancer-associated fibroblasts (CAFs).

Methods

Mammary fibroblasts from either female 8 weeks old PRDX1 knockout and wildtype mice or Balb/c mice were studied for characteristic protein expression using immunofluorescence and immunoblotting. Cancer-associated fibroblasts was examined by transwell migration and invasion assays. The binding of PRDX1 to JNK1 was assessed by co-immuneprecipitation and JNK regulation of CAF phenotypes was examined using the JNK inhibitor SP600125. Extracellular hydrogen peroxide levels were measured by chemiluminescence via the reaction between hypochlorite and luminol. Statistical analyses were done using Students t-test.

Results

We show here PRDX1 activity as an essential switch in regulating the activated phenotype as loss of PRDX1 results in the development of a CAF-like phenotype in mammary fibroblasts. We also show that PRDX1 regulates JNK kinase signaling thereby inhibiting CAF-like markers and CAF invasion. Inhibition of JNK activity reduced these behaviors.

Conclusions

These data suggest that PRDX1 repressed the activated phenotype of fibroblasts in part through JNK inhibition which may present a novel therapeutic option for CAF-enriched cancers such as breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-6031-4) contains supplementary material, which is available to authorized users.

Anti-Thermal Skin Aging Activity of Aqueous Extracts Derived from Apple Mint (Mentha suaveolens Ehrh.) in Human Dermal Fibroblasts

Thermal skin aging refers to skin aging induced by heat shock treatment. Apple mint (Mentha suaveolens Ehrh.) has been used as a folk medicine to treat various diseases. However, the activity of apple mint in thermal skin aging has yet to be investigated. In this study, we conducted various biological assays to demonstrate the anti-thermal skin aging activity of extracts of apple mint leaves (ALE). As a result, ALE showed significant antioxidant activities and inhibited the production of reactive oxygen species (ROS), matrix metalloproteinases (MMPs), and interleukin-8 (IL-8) as well as suppressed mitogen-activated proteins kinases (MAPKs) such as extracellular signal regulated kinases (ERK), c-Jun N terminal kinases (JNK), and p38 MAPK triggered by heat shock treatment in human dermal fibroblasts (HDFs). Consequently, ALE could be used as attractive cosmetic materials with anti-thermal skin aging activity.

Transcription Factor ETS-1 and Reactive Oxygen Species: Role in Vascular and Renal Injury

The E26 avian erythroblastosis virus transcription factor-1 (ETS-1) is a member of the ETS family and regulates the expression of a variety of genes including growth factors, chemokines and adhesion molecules. Although ETS-1 was discovered as an oncogene, several lines of research show that it is up-regulated by angiotensin II (Ang II) both in the vasculature and the glomerulus. While reactive oxygen species (ROS) are required for Ang II-induced ETS-1 expression, ETS-1 also regulates the expression of p47phox, which is one of the subunits of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and a major source of ROS in the kidney and vasculature. Thus, there appears to be a positive feedback between ETS-1 and ROS. ETS-1 is also upregulated in the kidneys of rats with salt-sensitive hypertension and plays a major role in the development of end-organ injury in this animal model. Activation of the renin angiotensin system is required for the increased ETS-1 expression in these rats, and blockade of ETS-1 or haplodeficiency reduces the severity of kidney injury in these rats. In summary, ETS-1 plays a major role in the development of vascular and renal injury and is a potential target for the development of novel therapeutic strategies to ameliorate end-organ injury in hypertension.

Selenoproteins and Metastasis

Cancer survival is largely impacted by the dissemination of cancer cells from the original tumor site to secondary tissues or organs through metastasis. Targets for antimetastatic therapies have recently become a focus of research, but progress will require a better understanding of the molecular mechanisms driving metastasis. Selenoproteins play important roles in many of the cellular activities underlying metastasis including cell adhesion, matrix degradation and migration, invasion into the blood and extravasation into secondary tissues, and subsequent proliferation into metastatic tumors along with the angiogenesis required for growth. In this review the roles identified for different selenoproteins in these steps and how they may promote or inhibit metastatic cancers is discussed. These roles include selenoenzyme modulation of redox tone and detoxification of reactive oxygen species, calcium homeostasis and unfolded protein responses regulated by endoplasmic reticulum selenoproteins, and the multiple physiological responses influenced by other selenoproteins.

Featured Article: Nanoenhanced matrix metalloproteinase-responsive delivery vehicles for disease resolution and imaging

The wide array of proteases, including matrix metalloproteinases, produced in response to many pathogenic insults, confers a unique proteolytic signature which is often disease specific and provides a potential therapeutic target for drug delivery. Here we propose the use of collagen-based nanoenhanced matrix metalloproteinase-responsive delivery vehicles that display matrix metalloproteinase-specific degradation in diverse in vitro models of proteolysis. We demonstrate that collagen particles comprised of protease substrates (primarily collagen) can be made of uniform size and loaded efficiently with assorted cargo including fluorescently labeled mesoporous silica, magnetic nanoparticles, proteins and antioxidants. We also demonstrate that pathologic concentrations of proteases produced in situ or in vitro display protease-specific cargo release. Additionally, we show that the collagen-based particles display bright fluorescence when loaded with a fluorophore, and have the potential to be used as vehicles for targeted delivery of drugs or imaging agents to regions of high proteolytic activity.

Exogenous C2 Ceramide Suppresses Matrix Metalloproteinase Gene Expression by Inhibiting ROS Production and MAPK Signaling Pathways in PMA-Stimulated Human Astroglioma Cells

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases, which play a pivotal role in invasion, migration, and angiogenesis of glioma. Therefore, controlling MMPs is potentially an important therapeutic strategy for glioma. In the present study, we found that exogenous cell-permeable short-chain C2 ceramide inhibits phorbol myristate acetate (PMA)-induced MMP-1, -3, and -9 gene expressions in U87MG and U373MG human astroglioma cells. In addition, C2 ceramide inhibited the protein secretion and enzymatic activities of MMP-1, -3, and -9. The Matrigel invasion assay and wound healing assay showed that C2 ceramide suppresses the in vitro invasion and migration of glioma cells, which appears to be involved in strong inhibition of MMPs by C2 ceramide. Subsequent mechanistic studies revealed that C2 ceramide inhibits PMA-induced mitogen-activated protein kinase (MAPK) phosphorylation and nuclear factor (NF)-κB/activator protein (AP)-1 DNA binding activities. Furthermore, C2 ceramide significantly inhibited PMA-induced reactive oxygen species (ROS) production and NADPH oxidase 4 (NOX4) expression, and inhibition of ROS by diphenylene iodonium (DPI, NADPH oxidase inhibitor) mimicked the effects of C2 ceramide on MMP expression and NF-κB/AP-1 via inhibition of p38 MAPK. The results suggest C2 ceramide inhibits MMP expression and glioma invasion, at least partly, by modulating ROS-p38 MAPK signaling axis and other MAPK signaling pathways.

Regulation of MMP-1 expression in response to hypoxia is dependent on the intracellular redox status of metastatic bladder cancer cells

High steady-state reactive oxygen species (ROS) production has been implicated with metastatic disease progression. We provide new evidence that this increased intracellular ROS milieu uniquely predisposes metastatic tumor cells to hypoxia-mediated regulation of the matrix metalloproteinase MMP-1. Using a cell culture metastatic progression model we previously reported that steady-state intracellular H2O2 levels are elevated in highly metastatic 253J-BV bladder cancer cells compared to their non-metastatic 253J parental cells. 253J-BV cells display higher basal MMP-1 expression, which is further enhanced under hypoxic conditions (1% O2). This hypoxia-mediated MMP-1 increase was not observed in the non-metastatic 253J cells. Hypoxia-induced MMP-1 increases are accompanied by the stabilization of hypoxia-inducible transcription factors (HIFs)-1α and HIF-2α, and a rise in intracellular ROS in metastatic 253J-BV cells. RNA interference studies show that hypoxia-mediated MMP-1 expression is primarily dependent on the presence of HIF-2α. Further, hypoxia promotes migration and spheroid outgrowth of only the metastatic 253J-BV cells and not the parental 253J cells. The observed HIF stabilization, MMP-1 expression and migration under hypoxia are dependent on increases in intracellular ROS, as these effects are attenuated by treatment with the antioxidant N-acetyl-L-cysteine. These data show that ROS play an important role in hypoxia-mediated MMP-1 expression and that an elevated intracellular redox environment, as observed in metastasis, predisposes tumor cells to an enhanced hypoxic response. It further supports the notion that metastatic tumor cells are uniquely able to utilize intracellular increases in ROS to drive pro-metastatic signaling events and highlights the important interplay between ROS and hypoxia in malignancy.

Regulation of signal transduction by reactive oxygen species in the cardiovascular system

Oxidative stress has long been implicated in cardiovascular disease, but more recently, the role of reactive oxygen species (ROS) in normal physiological signaling has been elucidated. Signaling pathways modulated by ROS are complex and compartmentalized, and we are only beginning to identify the molecular modifications of specific targets. Here, we review the current literature on ROS signaling in the cardiovascular system, focusing on the role of ROS in normal physiology and how dysregulation of signaling circuits contributes to cardiovascular diseases, including atherosclerosis, ischemia-reperfusion injury, cardiomyopathy, and heart failure. In particular, we consider how ROS modulate signaling pathways related to phenotypic modulation, migration and adhesion, contractility, proliferation and hypertrophy, angiogenesis, endoplasmic reticulum stress, apoptosis, and senescence. Understanding the specific targets of ROS may guide the development of the next generation of ROS-modifying therapies to reduce morbidity and mortality associated with oxidative stress.

Estrogen receptor beta and truncated variants enhance the expression of transfected MMP-1 promoter constructs in response to specific mechanical loading

Background

Joint diseases such as osteoarthritis (OA) predominantly afflict post-menopausal women, suggesting a pertinent role for female hormones. Estrogen receptor beta (ER-β) has been detected in connective tissues of the knee joint suggesting that these tissues are responsive to the hormone estrogen. Matrix metalloproteinase-1 (MMP-1) activity contributes to cartilage degradation, a key factor leading to OA development in synovial joints. Two polymorphic forms of MMP-1 exist due to a deletion/insertion of the guanine residue in the promoter, and the 2G allelic variant of MMP-1 exhibits more activity than the 1G allele. Previous studies have demonstrated that the polymorphic forms of the human MMP-1 are influenced by the modulating effects of estrogen receptor isoforms. In addition to hormonal influences, physiological factors such as altered mechanical loading are also contributory features of OA. In the present study, the combined influence of biomechanical and hormonal variables on the activity of MMP-1 isoforms was evaluated. We hypothesized that the combined effects of ER-β and sheer stress will differentially activate the two allelic forms of MMP-1 in a hormone-independent manner.

Methods

HIG-82 synoviocytes were transiently transfected with 1G or 2G alleles (±) ER-β and subjected to either shear or equibiaxial stress. Next, 1G/2G promoter activity was measured to determine the combined influence of physiological stimuli. Truncated ER-β constructs were used to determine the importance of different domains of ER-β on 1G/2G activation.

Results

The 2G allele exhibited a constitutively higher activity than the 1G allele, which was further increased when the transfected cells were subject to shear stress, but not equibiaxial stress. Moreover, the combination of ER-β and shear stress further increased the activity levels of the 1G/2G allelic variants. Additionally, select AF-2 truncated ER-β variants led to increased activity levels for the 2G allele, indicating the AF-1 domain was likely involved in the response to mechanical stimulation.

Conclusions

These results suggest that the 1G/2G alleles of MMP-1 are influenced by specific mechanical stimuli like shear stress, as well as the ER-β receptor. These findings contribute to the potential allelic involvement in connective tissue diseases such as OA in females compared to males.

Effects of Galla chinensis extracts on UVB-irradiated MMP-1 production in hairless mice

Galla chinensis (GAC) is a natural traditional Chinese medicine that has been widely used in folk medicine. Although GAC compounds (mainly gallic acid and methyl gallate) possess strong antiviral, antibacterial, anticancer, and antioxidant activities, there is no report regarding topical or oral administration of GAC compounds on UVB irradiation-induced photoaging in hairless mice (SKH: HR-1). In the present study, we examined cell viability, intracellular reactive oxygen species (ROS), matrix metalloproteinase-1 (MMP-1), and interleukin-6 (IL-6) in skin fibroblasts and keratinocytes induced by UVB in vitro. We also studied skin damage by measuring skin thickness, elasticity, wrinkling and levels of protein MMP-1, elastin, procollagen type I, and transforming growth factor-β1 (TGF-β1) in hairless mouse skin chronically irradiated by UVB in vivo. GAC treatment significantly prevented skin photoaging by reducing the levels of ROS, MMP-1, and IL-6 and promoting production of elastin, procollagen type I, and TGF-β1. According to the results of H&E staining and Masson's trichrome staining, GAC reduced skin thickness and wrinkle formation while it increased skin elasticity. The effects of GAC on UVB-induced skin photoaging may be due to suppressed MMP-1 expression. These findings could be referenced for the development of new agents that target UVB-induced photoaging.

Redox-sensitive gene-regulatory events controlling aberrant matrix metalloproteinase-1 expression

Aberrant matrix metalloproteinase-1 (MMP-1) expression contributes to the pathogenesis of many degenerative disease processes that are associated with increased oxidative damage or stress. We and others have established that shifts in steady-state H2O2 production resulting from enforced antioxidant gene expression, senescence, or UV irradiation control MMP-1 expression. Here we establish that histone deacetylase-2 (HDAC2) protein levels and its occupancy of the MMP-1 promoter are decreased in response to enforced manganese superoxide dismutase (Sod2) expression. Inhibition of HDAC activity further accentuates the redox-dependent expression of MMP-1. Sod2-dependent decreases in HDAC2 are associated with increases in a proteasome-sensitive pool of ubiquitinylated HDAC2 and MMP-1-specific histone H3 acetylation. Sod2 overexpression also enhanced recruitment of Ets-1, c-Jun, c-Fos, and the histone acetyltransferase PCAF to the distal and proximal regions of the MMP-1 promoter. Furthermore, the Sod2-dependent expression of MMP-1 can be reversed by silencing the transcriptional activator c-Jun. All of the above Sod2-dependent alterations are largely reversed by catalase coexpression, indicating that the redox control of MMP-1 is H2O2-dependent. These findings identify a novel redox regulation of MMP-1 transcription that involves site-specific promoter recruitment of both activating factors and chromatin-modifying enzymes, which converge to maximally drive MMP-1 gene expression.

Redox-relevant aspects of the extracellular matrix and its cellular contacts via integrins

SIGNIFICANCE

The extracellular matrix (ECM) fulfills essential functions in multicellular organisms. It provides the mechanical scaffold and environmental cues to cells. Upon cell attachment, the ECM signals into the cells. In this process, reactive oxygen species (ROS) are physiologically used as signalizing molecules.

RECENT ADVANCES

ECM attachment influences the ROS-production of cells. In turn, ROS affect the production, assembly and turnover of the ECM during wound healing and matrix remodeling. Pathological changes of ROS levels lead to excess ECM production and increased tissue contraction in fibrotic disorders and desmoplastic tumors. Integrins are cell adhesion molecules which mediate cell adhesion and force transmission between cells and the ECM. They have been identified as a target of redox-regulation by ROS. Cysteine-based redox-modifications, together with structural data, highlighted particular regions within integrin heterodimers that may be subject to redox-dependent conformational changes along with an alteration of integrin binding activity.

CRITICAL ISSUES

In a molecular model, a long-range disulfide-bridge within the integrin β-subunit and disulfide bridges within the genu and calf-2 domains of the integrin α-subunit may control the transition between the bent/inactive and upright/active conformation of the integrin ectodomain. These thiol-based intramolecular cross-linkages occur in the stalk domain of both integrin subunits, whereas the ligand-binding integrin headpiece is apparently unaffected by redox-regulation.

FUTURE DIRECTIONS

Redox-regulation of the integrin activation state may explain the effect of ROS in physiological processes. A deeper understanding of the underlying mechanism may open new prospects for the treatment of fibrotic disorders.

Escherichia coli infection induces mucosal damage and expression of proteins promoting urinary stone formation

The effect of urinary tract infection (UTI) on mucosal damage and production of proteins promoting urinary stone formation has not been elucidated. Osteopontin production, with associated mucosal damage due to UTI, may allow easier crystal retention and nucleation resulting in stone formation. The aim of this study is to demonstrate that expression of osteopontin (OPN), OPN mRNA, TLR-4, JNK, TNFR-1, iNOS, HMGB-1, and apoptosis process is higher than normal at renal tubular cells due to urinary tract infection by Escherichia coli. Adult male New Zealand strain rabbits were used. Thirty New Zealand strain rabbits were divided into three groups. The first group acted as controls, the second group underwent ligation of right ureter, and the third group underwent ligation of right ureter and injection of Escherichia coli 105/ml proximal to ligation. Nephrectomy and histological examination were performed after 5 days. All groups were HE stained to examine mucosal damage, specific monoclonal antibodies for TLR-4, JNK, mRNA OPN, OPN, TNFR-1, iNOS and HMGB-1. Apoptotic nuclei were demonstrated using TUNEL method. Statistical calculations were performed using ANOVA test, with p < 0.05 considered significant. The findings confirmed the hypothesis that infection of urinary tract by Escherichia coli demonstrated higher expression of OPN, OPN mRNA, TLR-4, JNK, TNFR-1, iNOS, HMGB-1, apoptosis process and mucosal damage than normal. Infection of urinary tract by Escherichia coli caused higher than normal expression of promoter protein osteopontin and mucosal damage at renal tubular cells. These suggest that urinary infection may promote stone formation by mucosal damage and elevate promoter protein osteopontin at tubulus cell, allowing easier crystal retention and nucleation.

Cellular redox, epigenetics and diseases

Since the Central dogma of Molecular Biology was proposed about 40 years ago; our understanding of the intricacies of gene regulation has undergone tectonic shifts almost every decade. It is now widely accepted that the complexity of an organism is not directed by the sheer number of genes it carries but how they are decoded by a myriad of regulatory modules. Over the years, it has emerged that the organizations chromatins and its remodeling; splicing and polyadenylation of pre-mRNAs, stability and localization of mRNAs and modulation of their expression by non-coding and miRNAs play pivotal roles in metazoan gene expression. Nevertheless, in spite of tremendous progress in our understanding of all these mechanisms of gene regulation, the way these events are coordinated leading towards a highly defined proteome of a given cell type remains enigmatic. In that context, the structures of many metazoan genes cannot fully explain their pattern of expression in different tissues, especially during embryonic development and progression of various diseases. Further, numerous studies done during the past quarter of a century suggested that the heritable states of transcriptional activation or repression of a gene can be influenced by the covalent modifications of constituent bases and associated histones; its chromosomal context and long-range interactions between various chromosomal elements (Holliday 1987; Turner 1998; Lyon 1993). However, molecular dissection of these phenomena is largely unknown and is an exciting topic of research under the sub-discipline epigenetics (Gasser et al. 1998).

Melatonin inhibits matrix metalloproteinase-9 (MMP-9) activation in the lipopolysaccharide (LPS)-stimulated RAW 264.7 and BV2 cells and a mouse model of meningitis

We explored anti-inflammatory potential of melatonin against the lipopolysaccharide (LPS)-induced inflammation in vivo and in vitro. RAW 264.7 and BV2 cells were stimulated by LPS, followed by the treatment with melatonin or vehicle at various time intervals. In a mouse model of meningitis induced by LPS, melatonin (5mg/kg) or vehicle was intravenously injected at 30min postinsult. The activity of matrix metalloproteinase-2 (MMP-2) and metalloproteinase-9 (MMP-9) was determined by gelatin zymography. Nuclear factor-kappa B (NFκB) translocation and binding activity were determined by immunocytochemistry and electrophoretic mobility shift assay (EMSA). Our results showed that either pretreatment or cotreatment with melatonin at 50-500 μm effectively inhibited the LPS-induced proMMP-9 activation in the RAW 264.7 and BV2 cells, respectively (P<0.05). This melatonin-induced proMMP-9 inhibition remained effective when treatment was delayed up to 2 and 6hr postinsult for RAW 264.7 and BV2 cells, respectively (P<0.05 for both groups). Additionally, melatonin significantly attenuated the rises of circulatory and cerebral MMP-9 activity, respectively (P<0.05) and reduced the loss of body weight (P<0.05) in mice with meningitis. Moreover, melatonin (50μm) effectively inhibited nuclear factor-kappa B (NFκB) translocation and binding activity in the LPS-treated RAW 264.7 and BV2 cells, respectively (P<0.05). These results demonstrate direct inhibitory actions of melatonin against postinflammatory NFκB translocation and MMP-9 activation and highlight its ability to inhibit systemic and cerebral MMP-9 activation following brain inflammation.

Hydrogen peroxide signaling is required for glucocorticoid-induced apoptosis in lymphoma cells

Glucocorticoid-induced apoptosis is exploited clinically for the treatment of hematologic malignancies. Determining the required molecular events for glucocorticoid-induced apoptosis will identify resistance mechanisms and suggest strategies for overcoming resistance. In this study, we found that glucocorticoid treatment of WEHI7.2 murine thymic lymphoma cells increased the steady-state [H(2)O(2)] and oxidized the intracellular redox environment before cytochrome c release. Removal of glucocorticoids after the H(2)O(2) increase resulted in a 30% clonogenicity; treatment with PEG-CAT increased clonogenicity to 65%. Human leukemia cell lines also showed increased H(2)O(2) in response to glucocorticoids and attenuated apoptosis after PEG-CAT treatment. WEHI7.2 cells that overexpress catalase (CAT2, CAT38) or were selected for resistance to H(2)O(2) (200R) removed enough of the H(2)O(2) generated by glucocorticoids to prevent oxidation of the intracellular redox environment. CAT2, CAT38, and 200R cells showed a 90-100% clonogenicity. The resistant cells maintained pERK survival signaling in response to glucocorticoids, whereas the sensitive cells did not. Treating the resistant cells with a MEK inhibitor sensitized them to glucocorticoids. These data indicate that: (1) an increase in H(2)O(2) is necessary for glucocorticoid-induced apoptosis in lymphoid cells, (2) increased H(2)O(2) removal causes glucocorticoid resistance, and (3) MEK inhibition can sensitize oxidative stress-resistant cells to glucocorticoids.

Manganese superoxide dismutase (Sod2) and redox-control of signaling events that drive metastasis

Manganese superoxide dismutase (Sod2) has emerged as a key enzyme with a dual role in tumorigenic progression. Early studies were primarily directed at defining the tumor suppressive function of Sod2 based on its low level expression in many tumor types. It is now commonly held that loss of Sod2 expression is likely an early event in tumor progression allowing for further propagation of the tumorigenic phenotype resulting from steady state increases in free radical production. Increases in free radical load have also been linked to defects in mitochondrial function and metastatic disease progression. It was initially believed that Sod2 loss may propagate metastatic disease progression, in reality both epidemiologic and experimental evidence indicate that Sod2 levels increase in many tumor types as they progress from early stage non-invasive disease to late stage metastatic disease. Sod2 overexpression in many instances enhances the metastatic phenotype that is reversed by efficient H(2)O(2) scavenging. This review evaluates the many sequelae associated with increases in Sod2 that impinge on the metastatic phenotype. The ability to use Sod2 to modulate the cellular redox-environment has allowed for the identification of redox-responsive signaling events that drive malignancy, such as invasion, migration and prolonged tumor cell survival. Further studies of these redox-driven events will help in the development of targeted therapeutic strategies to efficiently restrict redox-signaling essential for malignant progression.

Ets1 blocks terminal differentiation of keratinocytes and induces expression of matrix metalloproteases and innate immune mediators

The transcription factor Ets1 is normally expressed in the proliferative layer of stratified epithelium, but expression of Ets1 is significantly upregulated in squamous cell carcinomas. How elevated levels of Ets1 impact tumor initiation and progression is not well understood. To determine the biological consequences of overexpression of Ets1, we developed a transgenic mouse model that allows induction of Ets1 expression in keratinocytes of stratified epithelium in a regulatable fashion. Induction of Ets1 during embryonic development results in a dramatic alteration in epidermal structure and function by suppressing the expression of multiple stratum corneum constituents, while at the same time inducing expression of EGF ligands, AP1 transcription factors and matrix metalloproteases. Interestingly, expression of certain immune-related genes, including defensins, chemokines and cytokines was increased as well, suggesting a possible role for immune dysregulation in the promotion of squamous dysplasia. Experiments using cultured mouse keratinocytes indicate that Ets1 can induce expression of some of these mediators in a cell-intrinsic fashion. Collectively, our data reveal that elevated expression of Ets1 has a much broader array of pro-tumorigenic effects on epithelial cells than previously appreciated.

Features of vulnerable plaques and clinical outcome of UA/NSTEMI: Relationship with matrix metalloproteinase functional polymorphisms

OBJECTIVE

To assess the association of matrix metalloproteinases (MMP) genetic polymorphism (PM) with plaques vulnerability and clinical outcome of acute vascular events.

METHODS

MMP-1 (-1607 G in/del), MMP-3 (-1171 A in/del), and MMP-9 microsatellite ((13-26) CA repeats around -90) PMs have been determined (i) in 204 patients with cerebrovascular disease to assess the association with features of vulnerability in carotid plaques and prevalence of stroke, (ii) in 208 patients with UA/NSTEMI to assess the association with in-hospital clinical outcome.

RESULTS

Plaques from carriers of MMP-1 G insertion showed significantly smaller plaques and thicker fibrous cap. In CVD patients carrying such variant, Odds Ratio for previous stroke was 0.27 (95%C.I. 0.13-0.56, P=0.0002) and, in UA/NSTEMI patients, the risk of Major Adverse Cardiac Events (MACE, persistent angina, NSTEMI, and vascular death) was 0.22 (95%C.I. 0.11-0.44, P<0.0001). No variants in MMP-3 PM were associated to differences in either plaque features or clinical outcome. Carriers of MMP-9≥22 repeats in the microsatellite had larger plaques and lipid core. In CVD patients with such variant, Odds Ratio for stroke was 2.2 (95%C.I. 1.1-4.4) and, in UA/NSTEMI patients, MACE risk was 4.1 (95%C.I. 2.3-7.4, P<0.0001). Persistent angina and NSTEMI separately provided comparable results.

CONCLUSIONS

Carriers of MMP-1 G insertion show smaller and more stable plaques, as well as better prognosis in acute vascular events, while patients with ≥22 repeats in MMP-9 have larger necrotic core and worse prognosis in UA/NSTEMI.

Melatonin inhibits postischemic matrix metalloproteinase-9 (MMP-9) activation via dual modulation of plasminogen/plasmin system and endogenous MMP inhibitor in mice subjected to transient focal cerebral ischemia

We have shown that melatonin attenuated matrix metalloproteinase-9 (MMP-9) activation and decreased the risk of hemorrhagic transformation following cerebral ischemia-reperfusion. Herein, we investigate the possible involvement of the plasminogen/plasmin system and endogenous MMPs inhibitor underlying the melatonin-mediated MMP-9 inhibition. Mice were subjected to 1-hr ischemia and 48-hr reperfusion of the right middle cerebral artery. Melatonin (5 mg/kg) or vehicle was intravenously injected upon reperfusion. Brain infarction and hemorrhagic transformation were measured. Extracellular matrix damage was determined by Western immunoblot analysis for laminin protein. The activity and expression of MMP-2 and MMP-9 were determined by gelatin zymography, in situ zymography, and Western immunoblot analysis. In addition, the activities of tissue and urokinase plasminogen activators (tPA and uPA) were evaluated by plasminogen-dependent casein zymography. Endogenous plasminogen activator inhibitor (PAI) and tissue inhibitors of MMP (TIMP-1) were investigated using enzyme-linked immunosorbent assay (ELISA) and Western immunoblot analysis, respectively. Cerebral ischemia-reperfusion induced increased MMP-9 activity and expression at 12-48 hr after reperfusion onset. Relative to controls, melatonin-treated animals had significantly decreased MMP-9 activity and expression (P<0.05), in addition to reduced brain infarction and hemorrhagic transformation as well as improved laminin protein preservation. This melatonin-mediated MMP-9 inhibition was accompanied by reduced uPA activity (P<0.05), as well as increased TIMP-1 expression and PAI activity (P<0.05, respectively). These results demonstrate the melatonin's pluripotent mechanisms for attenuating postischemic MMP-9 activation and neurovascular damage, and further support it as an add-on to thrombolytic therapy for ischemic stroke patients.

Reactive oxygen species control senescence-associated matrix metalloproteinase-1 through c-Jun-N-terminal kinase

The lifetime exposure of organisms to oxidative stress influences many aging processes which involve the turnover of the extracellular matrix. In this study, we identify the redox-responsive molecular signals that drive senescence-associated (SA) matrix metalloproteinase-1 (MMP-1) expression. Precise biochemical monitoring revealed that senescent fibroblasts increase steady-state (H(2)O(2)) 3.5-fold (13.7-48.6 pM) relative to young cells. Restricting H(2)O(2) production through low O(2) exposure or by antioxidant treatments prevented SA increases in MMP-1 expression. The H(2)O(2)-dependent control of SA MMP-1 is attributed to sustained JNK activation and c-jun recruitment to the MMP-1 promoter. SA JNK activation corresponds to increases and decreases in the levels of its activating kinase (MKK-4) and inhibitory phosphatase (MKP-1), respectively. Enforced MKP-1 expression negates SA increases in JNK phosphorylation and MMP-1 production. Overall, these studies define redox-sensitive signaling networks regulating SA MMP-1 expression and link the free radical theory of aging to initiation of aberrant matrix turnover.

Redox-control of matrix metalloproteinase-1: a critical link between free radicals, matrix remodeling and degenerative disease

Many degenerative disease processes associated with aging result from enhanced extracellular matrix (ECM) breakdown. Concomitant with aberrant matrix destruction are alterations in levels of reactive oxygen species (ROS) generating and detoxification systems. ROS function as second messengers due to their ability to react with wide range of biomolecules resulting in modification of an array of signaling networks. ROS can activate upstream kinases (MKK) responsible for MAPK activation and restrict the activity of their inhibitory phosphatases. Here we focus on the redox-sensitive signaling components that control the expression of MMP-1, which is largely responsible for maintaining ECM homeostasis. Numerous disease processes are associated with shifts in steady state ROS levels that influence overall ECM degradation. This review highlights the redox-sensitive regulatory signals that control the expression of the primary initiating protease MMP-1 and provides strong rational for the use of antioxidant based therapies for treatment of degenerative disorders associated with aberrant matrix destruction.

Age-dependent increases in interstitial collagenase and MAP Kinase levels are exacerbated by superoxide dismutase deficiencies

Many age-associated degenerative diseases commonly involve degradation of the extracellular matrix and aberrant matrix metalloproteinase-1 (MMP-1) expression. In diverse cell lines MMP-1 or interstitial collagenase (CL) expression is tightly regulated through a network of signals involving reactive oxygen species (ROS). However, whether the in vivo age-associated increase in CL expression is also sensitive to ROS-mediated signaling has not been established. To evaluate the contribution of ROS to the age-dependent increase in CL we monitored the levels of murine CL in two well-established models of oxidant stress. Analysis of murine CL levels in mice deficient in either of the intracellular superoxide dismutases (Sod2(+/-) or Sod1(-/-)) revealed its age- and redox-dependent expression relative to WT controls. Both age- and redox-dependent increases in murine CL expression were associated with elevations in phosphorylation of the MAP Kinases, Erk, JNK and p38. CL expression was highest in renal and skeletal muscle tissue from the aged Sod1(-/-) mice and was associated with a decrease in collagen staining. These findings suggest that MAPK signaling and CL production are both age- and redox-responsive. The redox sensitivity of age-associated CL expression suggests that degenerative disease associated with aberrant matrix remodeling and oxidant stress may be amenable to antioxidant-based therapies.

Enhanced endothelial cell senescence by lithium-induced matrix metalloproteinase-1 expression

Endothelial cell (EC) senescence and dysfunction occurring after chronic injury and inflammation are highly associated with the development and progression of cardiovascular diseases. However, the factors involved in the establishment of EC senescence remain poorly understood. We have previously shown that lithium, an inhibitor of glycogen synthase kinase (GSK)-3beta and activator of the Wnt/beta-catenin signaling pathway, induces an EC senescent-like phenotype. Herein, we show that lithium induces a rapid and pronounced up-regulation of the matrix metalloproteinase (MMP)-1, an inflammation and senescent cell marker, at the mRNA and protein levels, whereas the induction of two other senescent cell markers is either weak (interleukin-8) or delayed (plasminogen activator inhibitor-1). Lithium effect on MMP-1 expression is also specific among other MMPs and not mediated by GSK3beta inhibition. Lithium affects MMP-1 expression mainly at the transcriptional level but neither the AP1/Ets regulatory sites nor the redox sensitive (-1607/2G) site in MMP-1 promoter are involved in lithium-dependent MMP-1 regulation. However, down-regulation of p53, a target of lithium in EC, dampens both basal and lithium-induced MMP-1 expression, which further links MMP-1 up-regulation with the establishment of cell senescence. Although increased MMP-1 levels are usually associated with angiogenesis in enabled proliferative EC, the exogenous addition of activated MMP-1 on lithium- arrested EC increases the number of EC positive for the senescent-associated-beta-galactosidase marker. Conversely, down-regulation of MMP-1 expression by small interfering RNAs blunts the lithium-dependent increase in senescent-associated-beta-galactosidase positive cells. Altogether our data indicate that lithium-induced MMP-1 may participate in the reinforcement of EC senescence and reveal a novel mechanism for lithium-induced tissue remodeling.

The role of p300 histone acetyltransferase in UV-induced histone modifications and MMP-1 gene transcription

Matrix metalloproteinase (MMP)-1 promotes ultraviolet (UV)-triggered long-term detrimental effects such as cancer formation and premature skin aging. Although histone modifications may play a crucial role in the transcriptional regulation of MMP-1, the relationship between UV-induced histone modification and MMP-1 expression is not completely understood. Here, we identify regulators of histone acetylation that may link UV-mediated DNA damage and MMP-1 induction by UV in cultured human dermal fibroblasts (HDFs) in vitro. UV irradiation of HDFs induced MMP-1 expression and increased the level of phosphorylation of H2AX (γ-H2AX), p53 and the acetylation of histone H3 (acetyl-H3). Total histone deacetylase (HDAC) enzymatic activity was decreased by UV irradiation, while histone acetyltransferase (HAT) activity was increased. Suppression of p300 histone acetyltransferase (p300HAT) activity by the p300HAT inhibitor anacardic acid (AA) or by down-regulation of p300 by siRNA prevented UV-induced MMP-1 expression and inhibited UV-enhanced γ-H2AX, p53 level, and acetyl-H3. Using chromatin immunoprecipitation assays, we observed that γ-H2AX, p53, acetyl-H3, p300 and c-Jun were consistently recruited by UV to a distinct region (−2067/−1768) adjacent to the p300 binding site (−1858/−1845) in the MMP-1 promoter. In addition, these recruitments of γ-H2AX, p53, acetyl-H3, p300 and c-Jun to the p300-2 site were significantly abrogated by post-treatment with AA. Furthermore, overexpression of p300 increased the basal and UV-induced MMP-1 promoter activity. Our results suggest that p300HAT plays a critical role in the transcriptional regulation of MMP-1 by UV.

Glutathione peroxidases in different stages of carcinogenesis

Cancer cells produce high amounts of reactive oxygen species (ROS) and evade apoptosis. Hydroperoxides support proliferation, invasion, migration and angiogenesis, but at higher levels induce apoptosis, thus being pro- and anti-carcinogenic. Accordingly, glutathione peroxidases (GPxs) regulating hydroperoxide levels might have dual roles too. GPx1, clearly an antioxidant enzyme, is down-regulated in many cancer cells. Its main role would be prevention of cancer initiation by ROS-mediated DNA damage. GPx2 is up-regulated in cancer cells. GPx1/GPx2 double knockout mice develop colitis and intestinal cancer. However, GPx2 knockdown cancer cells grow better in vitro and in vivo probably reflecting the physiological role of GPx2 in intestinal mucosa homeostasis. GPx2 counteracts COX-2 expression and PGE(2) production, which explains its potential to inhibit migration and invasion of cultured cancer cells. Overexpression of GPx3 inhibits tumor growth and metastasis. GPx4 is decreased in cancer tissues. GPx4-overexpressing cancer cells have low COX-2 activity and tumors derived therefrom are smaller than from control cells and do not metastasize. Collectively, GPxs prevent cancer initiation by removing hydroperoxides. GPx4 inhibits but GPx2 supports growth of established tumors. Metastasis, but also apoptosis, is inhibited by all GPxs. GPx-mediated regulation of COX/LOX activities may be relevant to early stages of inflammation-mediated carcinogenesis.

Direct progesterone receptor and indirect androgen receptor interactions with the kallikrein-related peptidase 4 gene promoter in breast and prostate cancer

Kallikrein 4 (KLK4) is a member of the human KLK gene family of serine proteases, many of which are implicated in hormone-dependent cancers. Like other KLKs, such as KLK3/PSA and KLK2, KLK4 gene expression is also regulated by steroid hormones in hormone-dependent cancers, although the transcriptional mechanisms are ill defined. Here, we have investigated the mechanisms mediating the hormonal regulation of KLK4 in breast (T47D) and prostate (LNCaP and 22Rv1) cancer cells. We have shown that KLK4 is only expressed in breast and prostate cancers that express the progesterone receptor (PR) and androgen receptor (AR), respectively. Expression analysis in PR- and AR-positive cells showed that the two predominant KLK4 variants that use either TIS1 or TIS2a/b are both up-regulated by progesterone in T47D cells and androgens in LNCaP cells. Two putative hormone response elements, K4.pPRE and K4.pARE at -2419 bp and -1005 bp, respectively, were identified in silico. Electrophoretic mobility shift assays and luciferase reporter experiments suggest that neither K4.pARE nor approximately 2.8 kb of the KLK4 promoter interacts directly with the AR to mediate KLK4 expression in LNCaP and 22Rv1 cells. However, we have shown that K4.pPRE interacts directly with the PR to up-regulate KLK4 gene expression in T47D cells. Further, chromatin immunoprecipitation experiments showed a time-dependent recruitment of the PR to the KLK4 promoter (-2496 to -2283), which harbors K4.pPRE. This is the first study to show that progesterone-regulated KLK4 expression in T47D cells is mediated partly by a hormone response element (K4.pPRE) at -2419 bp.

Mitochondria and metazoan epigenesis

In eukaryotes, mitochondrial activity controls ATP production, calcium dynamics, and redox state, thereby establishing physiological parameters governing the transduction of biochemical signals that regulate nuclear gene expression. However, these activities are commonly assumed to fulfill a 'housekeeping' function: necessary for life, but an epiphenomenon devoid of causal agency in the developmental flow of genetic information. Moreover, it is difficult to perturb mitochondrial function without generally affecting cell viability. For these reasons little is known about the extent of mitochondrial influence on gene activity in early development. Recent discoveries pertaining to the redox regulation of key developmental signaling systems together with the fact that mitochondria are often asymmetrically distributed in animal embryos suggests that they may contribute spatial information underlying differential specification of cell fate. In many cases such asymmetries correlate with localization of genetic determinants (i.e., mRNAs or proteins), particularly in embryos that rely heavily on cell-autonomous means of cell fate specification. In such embryos the localized genetic determinants play a dominant role, and any developmental information contributed by the mitochondria themselves is likely to be less obvious and more difficult to isolate experimentally. Hence, 'regulative' embryos that make more extensive use of conditional cell fate specification are better suited to experimental investigation of mitochondrial impacts on developmental gene regulation. Recent studies of the sea urchin embryo, which is a paradigmatic example of such a system, suggest that anisotropic distribution of mitochondria provides a source gradient of spatial information that directs epigenetic specification of the secondary axis via Nodal-Lefty signaling.

A new redox-dependent mechanism of MMP-1 activity control comprising reduced low-molecular-weight thiols and oxidizing radicals

Matrix metalloproteinases (MMPs), a family of zinc-dependent proteinases, participate in remodeling and degradation of the extracellular matrix proteins. The activity of MMPs is thought to be predominately posttranslationally regulated via proteolytic activation of precursor zymogens or via their naturally occurring endogenous inhibitors. Here, using recombinant MMP-1, we investigated new redox-dependent mechanisms of proteinase activity regulation by low-molecular-weight thiols. We find that glutathione (GSH), cysteine, homocysteine, and N-acetylcysteine at physiological concentrations competitively reduce MMP-1 activity up to 75% with an efficiency of cysteine > or = GSH > homocysteine > N-acetylcysteine. In contrast, S-derivatized thiols completely lack this inhibitory activity. Interestingly, the competitive GSH-mediated inhibition of MMP-1-activity can be fully reversed abrogated by oxidizing radicals like (*)NO(2) or Trolox radicals, here generated by UVA irradiation of nitrite or Trolox, two relevant agents in human skin physiology. This redox-dependent reactivation of the inactive GSH-MMP-1-complex comprises GSH oxidation and is significantly inhibited in the presence of ascorbic acid, an effective (*)NO(2) and Trolox radical scavenger. We here offer a new concept of redox-sensitive control of MMP-1 activity based on the inhibitory effect of reduced thiols and reactivation by a mechanism comprising derivatization or oxidation of the MMP-1-bound inhibitory-acting thiol.

Carbon monoxide, reactive oxygen signaling, and oxidative stress

The ubiquitous gas, carbon monoxide (CO), is of substantial biological importance, but apart from its affinity for reduced transition metals, particularly heme-iron, it is surprisingly nonreactive-as is the ferrous-carbonyl-in living systems. CO does form strong complexes with heme proteins for which molecular O2 is the preferred ligand and to which are attributed diverse physiological, adaptive, and toxic effects. Lately, it has become apparent that both exogenous and endogenous CO produced by heme oxygenase engender a prooxidant milieu in aerobic mammalian cells which initiates signaling related to reactive oxygen species (ROS) generation. ROS signaling contingent on CO can be segregated by CO concentration-time effects on cellular function, by the location of heme proteins, e.g., mitochondrial or nonmitochondrial sites, or by specific oxidation-reduction (redox) reactions. The fundamental responses to CO involve overt physiological regulatory events, such as activation of redox-sensitive transcription factors or stress-activated kinases, which institute compensatory expression of antioxidant enzymes and other adaptations to oxidative stress. In contrast, responses originating from highly elevated or protracted CO exposures tend to be nonspecific, produce untoward biological oxidations, and interfere with homeostasis. This brief overview provides a conceptual framework for understanding CO biology in terms of this physiological-pathological hierarchy.

Reactive oxygen species produced by NADPH oxidase, xanthine oxidase, and mitochondrial electron transport system mediate heat shock-induced MMP-1 and MMP-9 expression

In addition to ultraviolet radiation, human skin is also exposed to infrared radiation (IR) from natural sunlight. IR typically increases the skin temperature. This study examined whether or not heat shock-induced ROS stimulates MMPs in keratinocyte HaCaT cells. In HaCaT cells, heat shock was found to increase the intracellular ROS levels, including hydrogen peroxide and superoxide. The heat shock treatment induced MMP-1 and MMP-9, but not MMP-2, at the mRNA and protein levels. Moreover, heat shock caused the rapid activation of the three distinct MAPKs, ERK, JNK, and p38 kinase. The heat shock-induced expression of MMP-1 and MMP-9 was significantly suppressed by a pretreatment with the antioxidant NAC or catalase. On the other hand, SOD inhibited heat shock-induced activity of MMP-9 induction, but not MMP-1. A pretreatment with NAC or catalase, but not SOD, attenuated the phosphorylation of ERK, JNK, and p38 kinase by heat shock. The potential sites of ROS generation by heat shock along with its role in the heat shock-induced expression of MMP-1 and MMP-9 were next analyzed. These results indicate that heat shock-induced ROS is promoted via NADPH oxidase, xanthine oxidase, and mitochondria. Indeed, the NADPH oxidase and xanthine oxidase activities were increased by heat shock. Overall, the ROS produced by heat shock may play an important role in the heat shock-induced activation of MAPKs, which can induce MMP-1 and-9 expressions.

Redox signals in wound healing

Physical trauma represents one of the most primitive challenges that threatened survival. Healing a problem wound requires a multi-faceted comprehensive approach. First and foremost, the wound environment will have to be made receptive to therapies. Second, the appropriate therapeutic regimen needs to be identified and provided while managing systemic limitations that could secondarily limit the healing response. Unfortunately, most current solutions seem to aim at designing therapeutic regimen with little or no consideration of the specific details of the wound environment and systemic limitations. One factor that is centrally important in making the wound environment receptive is correction of wound hypoxia. Recent work have identified that oxygen is not only required to disinfect wounds and fuel healing but that oxygen-dependent redox-sensitive signaling processes represent an integral component of the healing cascade. Over a decade ago, it was proposed that in biological systems oxidants are not necessarily always the triggers for oxidative damage and that oxidants such as H2O2 could actually serve as signaling messengers and drive several aspects of cellular signaling. Today, that concept is much more developed and mature. Evidence supporting the role of oxidants such as H2O2 as signaling messenger is compelling. A complete understanding of the continuum between the classical and emergent roles of oxygen requires a thorough consideration of current concepts in redox biology. The objective of this review is to describe our current understanding of how redox-sensitive processes may drive dermal tissue repair.

The role of reactive oxygen species in integrin and matrix metalloproteinase expression and function

Cell adhesion and migration is largely dependent on integrin binding to extracellular matrix, and several signalling pathways involved in these processes have been shown to be modified by reactive oxygen species (ROS). In fact, integrin activation is linked to increased ROS production by NADPH-oxidases, 5-lipoxygenase, and release from mitochondria. Cell migration is intimately linked to degradation of the extracellular matrix, and activated matrix metalloproteinases (MMPs) are a prerequisite for cancer cell invasion and metastasis. In this minireview, we focus on the interplay between integrin-mediated ROS production and MMP expression as well as its biological and pathobiological significance.