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

Candidate genes associated with reproductive traits in rabbits

In the era of scientific advances and genetic progress, opportunities in the livestock sector are constantly growing. The application of molecular-based methods and approaches in farm animal breeding would accelerate and improve the expected results. The current work aims to comprehensively review the most important causative mutations in candidate genes that affect prolificacy traits in rabbits. Rabbits are a source of excellent-tasting meat that is high in protein and low in fat. Their early maturity and intensive growth are highly valued all over the world. However, improving reproductive traits and prolificacy in rabbits could be very tricky with traditional selection. Therefore, traditional breeding programs need new methods based on contemporary discoveries in molecular biology and genetics because of the complexity of the selection process. The study and implementation of genetic markers related to production in rabbits will help to create populations with specific productive traits that will produce the desired results in an extremely short time. Many studies worldwide showed an association between different genes and productive traits in rabbits. The study of these polymorphisms and their effects could be useful for molecular-oriented breeding, particularly marker-assisted selection programs in rabbit breeding.

Identification of the promoter region regulating the transcription of the REV7 gene

REV7 is involved in various biological processes including DNA repair and mutagenesis, cell cycle regulation, gene transcription, and carcinogenesis. REV7 is highly expressed in adult testicular germ cells as well as several malignant tumors. REV7 expression levels are associated with prognosis in several human cancers, however, the mechanism of REV7 transcriptional regulation has not been elucidated. In this study, we characterized the promoter region of the REV7 gene. A luciferase reporter assay using the human germ cell tumor cell line NEC8 was utilized to examine the upstream genomic region of REV7 for transcriptional activity, and two transcriptional activation regions were identified. We determined a small genomic region important for transcriptional activation using site-directed mutagenesis; this region is shared by several putative binding motifs for transcription factors, including the cAMP-responsive element modulator (CREM), cAMP-response element binding protein (CREB), and B-lymphocyte-induced maturation protein-1 (BLIMP-1). Exogenous CREM and CREB expression had no effect on the transcriptional activity in NEC8 cells or the human embryonic kidney cell line HEK293T. In contrast, exogenous BLIMP-1 expression increased luciferase reporter activity in HEK293T cells but unexpectedly decreased activity in NEC8 cells. Chromatin immunoprecipitation analysis demonstrated that BLIMP-1 binds to the genomic region near the binding motif in the REV7 promoter. Additionally, BLIMP-1 overexpression promoted endogenous REV7 expression in HEK293T cells. These findings suggest that BLIMP-1 may be a putative transcriptional regulator of REV7 in mammalian cells.

PAI-1, the Plasminogen System, and Skeletal Muscle

The plasminogen system is a critical proteolytic system responsible for the remodeling of the extracellular matrix (ECM). The master regulator of the plasminogen system, plasminogen activator inhibitor-1 (PAI-1), has been implicated for its role in exacerbating various disease states not only through the accumulation of ECM (i.e., fibrosis) but also its role in altering cell fate/behaviour. Examination of PAI-1 has extended through various tissues and cell-types with recent investigations showing its presence in skeletal muscle. In skeletal muscle, the role of this protein has been implicated throughout the regeneration process, and in skeletal muscle pathologies (muscular dystrophy, diabetes, and aging-driven pathology). Needless to say, the complete function of this protein in skeletal muscle has yet to be fully elucidated. Given the importance of skeletal muscle in maintaining overall health and quality of life, it is critical to understand the alterations—particularly in PAI-1—that occur to negatively impact this organ. Thus, we provide a comprehensive review of the importance of PAI-1 in skeletal muscle health and function. We aim to shed light on the relevance of this protein in skeletal muscle and propose potential therapeutic approaches to aid in the maintenance of skeletal muscle health.

Protein deregulation associated with breast cancer metastasis

Breast cancer is one of the most prevalent malignancies worldwide. It consists of a group of tumor cells that have the ability to grow uncontrollably, overcome replicative senescence (tumor progression) and metastasize within the body. Metastases are processes that consist of an array of complex gene dysregulation events. Although these processes are still not fully understood, the dysregulation of a number of key proteins must take place if the tumor cells are to disseminate and metastasize. It is now widely accepted that future effective and innovative treatments of cancer metastasis will have to encompass all the major components of malignant transformation. For this reason, much research is now being carried out into the mechanisms that govern the malignant transformation processes. Recent research has identified key genes involved in the development of metastases, as well as their mechanisms of action. A detailed understanding of the encoded proteins and their interrelationship generates the possibility of developing novel therapeutic approaches. This review will focus on a select group of proteins, often deregulated in breast cancer metastasis, which have shown therapeutic promise, notably, EMT, E-cadherin, Osteopontin, PEA3, Transforming Growth Factor Beta (TGF-β) and Ran.

Tissue inhibitor of metalloproteinases (TIMPs) in heart failure

Remodeling of the myocardium and the extracellular matrix (ECM) occurs in heart failure irrespective of its initial cause. The ECM serves as a scaffold to provide structural support as well as housing a number of cytokines and growth factors. Hence, disruption of the ECM will result in structural instability as well as activation of a number of signaling pathways that could lead to fibrosis, hypertrophy, and apoptosis. The ECM is a dynamic entity that undergoes constant turnover, and the integrity of its network structure is maintained by a balance in the function of matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitor of metalloproteinases (TIMPs). In heart disease, levels of MMPs and TIMPs are altered resulting in an imbalance between these two families of proteins. In this review, we will discuss the structure, function, and regulation of TIMPs, their MMP-independent functions, and their role in heart failure. We will review the knowledge that we have gained from clinical studies and animal models on the contribution of TIMPs in the development and progression of heart disease. We will further discuss how ECM molecules and regulatory genes can be used as biomarkers of disease in heart failure patients.

Extracellular regulated kinase 1/2 signaling is a critical regulator of interleukin-1β-mediated astrocyte tissue inhibitor of metalloproteinase-1 expression

Astrocytes are essential for proper central nervous system (CNS) function and are intricately involved in neuroinflammation. Despite evidence that immune-activated astrocytes contribute to many CNS pathologies, little is known about the inflammatory pathways controlling gene expression. Our laboratory identified altered levels of tissue inhibitor of metalloproteinase (TIMP)-1 in brain lysates from human immunodeficiency virus (HIV)-1 infected patients, compared to age-matched controls, and interleukin (IL)-1β as a key regulator of astrocyte TIMP-1. Additionally, CCAAT enhancer binding protein (C/EBP)β levels are elevated in brain specimens from HIV-1 patients and the transcription factor contributes to astrocyte TIMP-1 expression. In this report we sought to identify key signaling pathways necessary for IL-1β-mediated astrocyte TIMP-1 expression and their interaction with C/EBPβ. Primary human astrocytes were cultured and treated with mitogen activated protein kinase-selective small molecule inhibitors, and IL-1β. TIMP-1 and C/EBPβ mRNA and protein expression were evaluated at 12 and 24 h post-treatment, respectively. TIMP-1 promoter-driven luciferase plasmids were used to evaluate TIMP-1 promoter activity in inhibitor-treated astrocytes. These data show that extracellular regulated kinase (ERK) 1/2-selective inhibitors block IL-1β-induced astrocyte TIMP-1 expression, but did not decrease C/EBPβ expression in parallel. The p38 kinase (p38K) inhibitors partially blocked both IL-1β-induced astrocyte TIMP-1 expression and C/EBPβ expression. The ERK1/2-selective inhibitor abrogated IL-1β-mediated increases in TIMP-1 promoter activity. Our data demonstrate that ERK1/2 activation is critical for IL-1β-mediated astrocyte TIMP-1 expression. ERK1/2-selective inhibition may elicit a compensatory response in the form of enhanced IL-1β-mediated astrocyte C/EBPβ expression, or, alternatively, ERK1/2 signaling may function to moderate IL-1β-mediated astrocyte C/EBPβ expression. Furthermore, p38K activation contributes to IL-1β-induced astrocyte TIMP-1 and C/EBPβ expression. These data suggest that ERK1/2 signals downstream of C/EBPβ to facilitate IL-1β-induced astrocyte TIMP-1 expression. Astrocyte ERK1/2 and p38K signaling may serve as therapeutic targets for manipulating CNS TIMP-1 and C/EBPβ levels, respectively.

Cilostazol inhibits matrix invasion and modulates the gene expressions of MMP-9 and TIMP-1 in PMA-differentiated THP-1 cells

The invasion of monocytes into the subendothelium space plays an important role in the early stage of atherosclerosis. Cilostazol, a specific phosphodiesterase type III (PDE3) inhibitor, has been shown to exhibit anti-atherosclerotic effect. The present study aimed to investigate the modulating effects of cilostazol on monocyte invasion and the gene expressions of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1. We found that PMA significantly increased the invasive ability and the MMP-9 activity of THP-1 cells, as analyzed by matrix invasion assay and gelatin zymography, respectively. The increased expression of MMP-9 was demonstrated at both the RNA and protein levels by RT/real-time PCR and western blot analysis. These changes were markedly inhibited by cilostazol in a dose-dependent manner, which also could be observed when cAMP analog was used. On the contrary, the expression of TIMP-1, an inhibitor of MMP-9, was significantly upregulated by cilostazol dose dependently at both the RNA and protein levels. Reverse zymography further confirmed the increase of TIMP-1 activity after cilostazol treatment. The increase of TIMP-1 by cilostazol, however, was not cAMP-dependent. Cilostazol reduced the MMP-9 promoter activity and suppressed the nuclear translocation of NF-κB, indicating that the inhibitory effect of cilostazol is at the transcriptional level. In conclusion, the present study provides an additional mechanism underlying the anti-atherosclerotic effect of cilostazol by inhibiting the monocyte invasion and modulating the gene expressions of MMP-9 and TIMP-1 in monocytes upon differentiating to macrophages.

CCAAT/enhancer binding protein β expression is increased in the brain during HIV-1-infection and contributes to regulation of astrocyte tissue inhibitor of metalloproteinase-1

Human immunodeficiency virus (HIV)-1-associated neurocognitive disorders (HAND) associated with infection and activation of mononuclear phagocytes (MP) in the brain, occur late in disease. Infected/activated MP initiate neuroinflammation activating glial cells and ultimately disrupting neuronal function. Astrocytes secrete tissue inhibitor of metalloproteinase (TIMP)-1 in response to neural injury. Altered TIMP-1 levels are implicated in several CNS diseases. CCAAT enhancer-binding protein β (C/EBPβ), a transcription factor, is expressed in rodent brains in response to neuroinflammation, implicating it in Alzheimer's, Parkinson's, and HAND. Here, we report that C/EBPβ mRNA levels are elevated and its isoforms differentially expressed in total brain tissue lysates of HIV-1-infected and HIV-1 encephalitis patients. In vitro, HAND-relevant stimuli additively induce C/EBPβ nuclear expression in human astrocytes through 7 days of treatment. Over-expression of C/EBPβ increases TIMP-1 promoter activity, mRNA, and protein levels in human astrocytes activated with interleukin-1β. Knockdown of C/EBPβ with siRNA decreases TIMP-1 mRNA and protein levels. These data suggest that C/EBPβ isoforms are involved in complex regulation of astrocyte TIMP-1 production during HIV-1 infection; however, further studies are required to completely understand their role during disease progression.

Interleukin-18 induces EMMPRIN expression in primary cardiomyocytes via JNK/Sp1 signaling and MMP-9 in part via EMMPRIN and through AP-1 and NF-kappaB activation

IL-18 and the extracellular matrix metalloproteinase (MMP) inducer (EMMPRIN) stimulate the expression of proinflammatory cytokines and MMPs and are elevated in myocardial hypertrophy, remodeling, and failure. Here, we report several novel findings in primary cardiomyocytes treated with IL-18. First, IL-18 activated multiple transcription factors, including NF-κB (p50 and p65), activator protein (AP)-1 (cFos, cJun, and JunD), GATA, CCAAT/enhancer-binding protein, myocyte-specific enhancer-binding factor, interferon regulatory factor-1, p53, and specific protein (Sp)-1. Second, IL-18 induced EMMPRIN expression via myeloid differentiation primary response gene 88/IL-1 receptor-associated kinase/TNF receptor-associated factor-6/JNK-dependent Sp1 activation. Third, IL-18 induced a number of MMP genes, particularly MMP-9, at a rapid rate as well as tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-3 at a slower rate. Finally, the IL-18 induction of MMP-9 was mediated in part via EMMPRIN and through JNK- and ERK-dependent AP-1 activation and p38 MAPK-dependent NF-κB activation. These results suggest that the elevated expression of IL-18 during myocardial injury and inflammation may favor EMMPRIN and MMP induction and extracellular matrix degradation. Therefore, targeting IL-18 or its signaling pathways may be of potential therapeutic benefit in adverse remodeling.

EMMPRIN activates multiple transcription factors in cardiomyocytes, and induces interleukin-18 expression via Rac1-dependent PI3K/Akt/IKK/NF-kappaB andMKK7/JNK/AP-1 signaling

The transmembrane glycoprotein extracellular matrix metalloproteinase inducer (EMMPRIN), and the pleiotropic proinflammatory cytokine interleukin (IL)-18, play critical roles in myocardial remodeling, by inducing matrix degrading metalloproteinases (MMPs). Previously we showed that IL-18 induces EMMPRIN expression in cardiomyocytes via MyD88/IRAK4/TRAF6/JNK-dependent Sp1 activation. Here in reciprocal studies we demonstrate that EMMPRIN is a potent inducer of IL-18 transcription, protein expression and protein secretion in primary mouse cardiomyocytes. We show for the first time that EMMPRIN stimulates the activation of NF-kappaB, AP-1, CREB, and ATF-2 in cardiomyocytes, and induces IL-18 expression via Rac1-dependent PI3K/Akt/IKK/NF-kappaB and MKK7/JNK/AP-1 signaling. Moreover, EMMPRIN induces robust time-dependent induction of various MMP mRNAs. EMMPRIN also induces the mRNA of TIMPs 1 and 3, but in a delayed fashion. These results suggest that IL-18-induced EMMPRIN expression may favor net MMP expression and ECM destruction, and thus identify both as potential therapeutic targets in countering adverse myocardial remodeling.

Activator protein-2 impairs the invasion of a human extravillous trophoblast cell line

The reduced migration/invasion of extravillous trophoblasts (EVTs) is a key feature of the genesis of preeclampsia. We and others previously reported that transcriptional factors activator protein-2 (AP-2) alpha and AP-2gamma act as suppressors of tumor invasion. The present study examined the expressions of AP-2alpha and AP-2gamma in preeclamptic placenta vs. control placenta and investigated their effect on the function of EVTs. The expressions of AP-2alpha and AP-2gamma were elevated in the preeclamptic placentas in comparison with the gestational age-matched control placentas. Their expressions also increased in EVTs of the preeclamptic placentas. Thereafter, we transfected AP-2alpha or AP-2gamma into human EVT cell line, HTR-8/SVneo. The overexpression of AP-2alpha or AP-2gamma decreased the migratory and invasive abilities in HTR-8/SVneo cells. This was followed by the reduction of protease activated receptor-1 and matrix metalloproteinases and a significant induction of plasminogen activator inhibitor-1 and the tissue inhibitor of metalloproteinase-1. AP-2alpha and AP-2gamma were weakly expressed in the cultured EVTs and HTR-8/SVneo cells, whereas they were induced by TNF-alpha, which increases in preeclamptic placenta and impairs trophoblast invasion. In the presence of TNF-alpha, the invasion of the HTR-8/SVneo cells was partially restored by a blocking of AP-2 induction using small interfering RNA of AP-2. The present data suggest that AP-2 may suppress trophoblast migration and invasion, thus leading to a shallow placentation in preeclampsia.

Transcriptional regulation of hepatic stellate cells

Hepatic stellate cell (HSC) activation is a process of cellular transdifferentiation in which, upon liver injury, the quiescent vitamin A storing perisinusoidal HSC is converted into a wound-healing myofibroblast and acquires potent pro-inflammatory and pro-fibrogenic activities. This remarkable phenotypic transformation is underpinned by changes in the expression of a vast number of genes. In this review we survey current knowledge of the transcription factors that either control HSC activation or which regulate specific fibrogenic functions of the activated HSC such as collagen expression, proliferation and resistance to apoptosis.

Recent perspectives on the genetic background of neural tube defects with special regard to iniencephaly

Iniencephaly is a rare and mostly lethal type of neural tube defect. The pattern of inheritance of this group of malformations is multifactorial, rendering the identification of the underlying causes. Numerous studies have been conducted to elucidate the genetic basis of human neurulation. Essential signaling pathways of the development of the CNS include the planar cell polarity pathway, which is important for the initiation of neural tube closure, as well as the sonic hedgehog pathway, which regulates the neural plate bending. Genes influencing the different stages of neurulation have been investigated for their eventual role in the development of these malformations. Among the environmental factors, folic acid seems to be the most important modifier of the risk of human neural tube defects. Genes of the folate metabolism pathways have also been investigated to identify mutations resulting in increased risk of neural tube defects. In this review we have attempted to summarize the knowledge on iniencephaly and neural tube defects, with special regard to genetic factors of the etiology.

A 19-base pair deletion polymorphism in dihydrofolate reductase is associated with increased unmetabolized folic acid in plasma and decreased red blood cell folate

Dihydrofolate reductase (DHFR) catalyzes the reduction of folic acid to tetrahydrofolate (THF). A 19-bp noncoding deletion allele maps to intron 1, beginning 60 bases from the splice donor site, and has been implicated in neural tube defects and cancer, presumably by influencing folate metabolism. The functional impact of this polymorphism has not yet been demonstrated. The objective of this research was to determine the effects of the DHFR mutation with respect to folate status and assess influence of folic acid intake on these relations. The relationship between DHFR genotype and plasma concentrations of circulating folic acid, total folate, total homocysteine, and concentrations of RBC folate was determined in 1215 subjects from the Framingham Offspring Study. There was a significant interaction between DHFR genotype and folic acid intake with respect to the prevalence of high circulating unmetabolized folic acid (defined as >85th percentile). Folic acid intake of >or=500 microg/d increased the prevalence of high circulating unmetabolized folic acid in subjects with the deletion (del/del genotype (47.0%) compared with the wild type (WT)/del (21.4%) and wild type (WT)/WT genotypes (24.4%) (P for interaction = 0.03). Interaction between the DHFR polymorphism and folic acid intake was also seen with respect to RBC folate (P for interaction = 0.01). When folic acid intake was <250 microg/d, the del/del genotype was associated with significantly lower RBC folate (732.3 nmol/L) compared with the WT/WT genotype (844.4 nmol/L). Our results suggest the del/del polymorphism in DHFR is a functional polymorphism, because it limits assimilation of folic acid into cellular folate stores at high and low folic acid intakes.

An insertion/deletion polymorphism of the dihydrofolate reductase (DHFR) gene is associated with serum and red blood cell folate concentrations in women

A low serum folate and high homocysteine phenotype is associated with an increased risk of neural tube defects (NTDs), cardiovascular diseases and other pathologies. Thus defining both genetic and non-genetic factors that may impact folate/homocysteine metabolism will enhance our understanding of the etiologic mechanisms underlying these conditions and facilitate risk assessment. Dihydrofolate reductase catalyzes the reduction of folic acid to dihydrofolate and thereafter to tetrahydrofolate. The impact of the dihydrofolate reductase (DHFR) c.86 + 60_78 insertion/deletion (ins/del) polymorphism on folate and homocysteine concentrations was analyzed using data from healthy young adults from Northern Ireland, collected as part of visit three of the Young Hearts Project. Among men the DHFR c.86 + 60_78 polymorphism was not significantly associated with serum or red blood cell folate concentrations, or with homocysteine concentrations. Among women the DHFR c.86 + 60_78 polymorphism explained 2% of the variation in RBC folate levels and 5% of the variation in serum folate levels, but did not appear to have an independent effect on homocysteine. Relative to women with the DHFR c.86 + 60_78 ins/ins and ins/del genotypes, del/del homozygotes had increased serum and red blood cell folate concentrations and may therefore be at decreased risk of having offspring affected by NTDs and of other adverse reproductive and health outcomes attributable to low folate.

A functional 19-base pair deletion polymorphism of dihydrofolate reductase (DHFR) and risk of breast cancer in multivitamin users

BACKGROUND

Dihydrofolate reductase (DHFR) converts dihydrofolate (DHF) into tetrahydrofolate (THF) and plays an essential role in cell metabolism and cellular growth. Folic acid from multivitamins needs to be reduced by DHFR before it participates in cellular reactions.

OBJECTIVES

We examined the relation of a 19-base pair (bp) deletion polymorphism of the DHFR gene with the risk of breast cancer by using data from the Long Island Breast Cancer Study Project, a population-based case-control study. We also investigated the transcriptional effect of this deletion polymorphism.

DESIGN

Dietary data and habitual use of multivitamins were assessed from a modified Block food-frequency questionnaire (FFQ). Genotypes of DHFR were ascertained from 1062 case subjects and 1099 control subjects by allele-specific polymerase chain reaction. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% CIs.

RESULT

Although the DHFR 19-bp deletion polymorphism was not associated with overall breast cancer risk, we observed a borderline significant additive interaction (P = 0.06) between the DHFR genotype and multivitamin use. The -19-bp allele was associated with greater breast cancer risk in multivitamin users (51.2% of the study population) with an OR of 1.26 (95% CI: 0.96, 1.66) and 1.52 (95% CI: 1.08, 2.13) for the +/- and -/- genotypes, respectively (P for trend = 0.02) than in multivatimin nonusers. A dose-dependent relation (P for trend < 0.001) between DHFR expression and the deletion genotype was observed. Compared with the subjects with the 19-bp +/+ genotype, subjects with the -/- genotype had 4.8-fold DHFR mRNA levels.

CONCLUSIONS

The DHFR 19-bp deletion polymorphism affects the transcription of DHFR gene in humans. Multivitamin supplements may place a subgroup of women (ie, those with the -19-bp allele) at elevated risk of developing breast cancer.

Activator protein-2 in carcinogenesis with a special reference to breast cancer-A mini review

Activator protein-2 (AP-2) transcription factors are involved in the regulation of cell proliferation, differentiation, apoptosis and carcinogenesis. AP-2alpha has been suggested to function as a tumor suppressor in many cancers and AP-2gamma to be a marker of testicular and germ cell malignancies. At least 3 of the 5 AP-2 family members identified to date, AP-2alpha, AP-2beta and AP-2gamma, are known to be expressed in breast tissue and thought to coordinate the growth and development of the breast via regulation of several breast-related genes such as human epidermal growth factor receptor-2 (HER2) and estrogen receptor (ER). The function of AP-2alpha seems to be tumor suppressive in breast tissue, whereas the role of the other AP-2 family members is less well known. In this review, we summarize the current knowledge of AP-2 in carcinogenesis, especially in breast cancer.

Dexamethasone induces the expression of metalloproteinase inhibitor TIMP-1 in the murine cerebral vascular endothelial cell line cEND

In many neuroinflammatory conditions, including multiple sclerosis (MS), encephalitis, meningitis, brain tumours and cerebral ischaemia, the matrix metalloproteinases (MMPs) play an important role in disrupting the blood-brain barrier (BBB). Normally under tight regulation, increased MMP-9 cerebrospinal fluid levels and excessive proteolytic activity is detected in the blood and cerebrospinal fluid in patients with acute MS. MMP-9 is a member of the type IV collagenases, which attack components of the endothelial basal lamina, including type IV collagen. The disruption of the BBB and clinical symptoms can be reduced with different inhibitors to MMPs including activators of tissue inhibitor of metalloproteinases-1 (TIMP-1), the cognate tissue inhibitor of MMP-9. Since intravenous glucocorticoid (GC) treatment reduces the levels of MMP-9 markedly in patients, we hypothesized that GC effects might be mediated by transcriptional activation of the TIMP-1 gene in addition to reported repressive effects on MMP-9 transcription. Our results provide direct evidence that GCs increase TIMP-1 in the brain endothelial cell line cEND, prevent alterations in microvascular integrin alpha1 subunit expression and help maintain endothelial barrier function in response to pro-inflammatory stimuli (TNFalpha administration). GC-induced up-regulation of TIMP-1 expression by the CNS vascular endo-thelium may thus play a role in preservation of the endothelial basal lamina and maintain integrin alpha1 and tight junction protein expression important for vessel wall integrity.

Actinobacillus actinomycetemcomitans lipopolysaccharide regulates matrix metalloproteinase, tissue inhibitors of matrix metalloproteinase, and plasminogen activator production by human gingival fibroblasts: A potential role in connective tissue destructio

Fibroblasts, a major constituent of gingival connective tissue, can produce immunoregulatory cytokines and proteolytic enzymes that may contribute to tissue destruction. In this study, we evaluated the production of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and plasminogen activators by gingival fibroblasts stimulated with lipopolysaccharides (LPS) produced by periodontopathogens, including Actinobacillus actinomycetemcomitans. In addition, changes in the expression and phosphorylation state of fibroblast intracellular signaling proteins induced by A. actinomycetemcomitans LPS were characterized using antibody microarrays. We showed that A. actinomycetemcomitans LPS induced the production of a 50 kDa plasminogen activator, MMP-2 and, to a lesser extent, MMP-3 by fibroblasts. The stimulation of fibroblasts with A. actinomycetemcomitans LPS also resulted in the overproduction of TIMP-1, but had no effect on the production of TIMP-2. Comparable responses were also obtained with Porphyromonas gingivalis and Fusobacterium nucleatum subsp. nucleatum LPS. The results of the microarray analyses showed that A. actinomycetemcomitans LPS induced changes in the phosphorylation state and expression of gingival fibroblast intracellular signaling proteins. More specifically, they suggested that A. actinomycetemcomitans LPS may induce both Jun N-terminus protein-serine kinases (JNK) and mitogen-activated protein-serine kinase p38 alpha (p38alpha MAPK) pathway activation, leading to increased activator protein-1 (AP-1) and nuclear factor kappa-B (NFkappaB) activities, which in turn can stimulate MMP-2, MMP-3, TIMP-1, and urokinase-type plasminogen activator (uPA) expression. This may contribute to periodontal connective tissue destruction.

JunD is a profibrogenic transcription factor regulated by Jun N-terminal kinase-independent phosphorylation

JunD is implicated in the regulation of hepatic stellate cell (HSC) activation and liver fibrosis via its transcriptional regulation of the tissue inhibitor of metalloproteinases-1 (TIMP-1) gene. In the present study we found in vivo evidence of a role for JunD in fibrogenesis. Expression of JunD was demonstrated in alpha-SMA-positive activated HSCs of fibrotic rodents and human livers. The junD-/- mice were protected from carbon tetrachloride-induced fibrosis. The livers of injured junD-/- mice displayed significantly reduced formation of fibrotic crosslinked collagen and a smaller number of alpha-SMA-positive HSCs compared with those of wild-type (wt) mice. Hepatic TIMP-1 mRNA expression in injured junD-/- mice was 78% lower and in culture activated junD-/- HSCs was 50%-80% lower than that in wt mice. In examining the signal transduction mechanisms that regulate JunD-dependent TIMP-1 expression, we found a role for phosphorylation of the Ser100 residue of JunD but ruled out JNK as a mediator of this event, suggesting ERK1/2 is utilized. In conclusion, a signaling pathway for the development of fibrosis involves the regulation of TIMP-1 expression by phosphorylated JunD.

Isoginkgetin inhibits tumor cell invasion by regulating phosphatidylinositol 3-kinase/Akt-dependent matrix metalloproteinase-9 expression

Matrix metalloproteinase (MMP)-9 plays a key role in tumor invasion. Inhibitors of MMP-9 were screened from Metasequoia glyptostroboides (Dawn redwood) and one potent inhibitor, isoginkgetin, a biflavonoid, was identified. Noncytotoxic levels of isoginkgetin decreased MMP-9 production profoundly, but up-regulated the level of tissue inhibitor of metalloproteinase (TIMP)-1, an inhibitor of MMP-9, in HT1080 human fibrosarcoma cells. The major mechanism of Ras-dependent MMP-9 production in HT1080 cells was phosphatidylinositol 3-kinase (PI3K)/Akt/nuclear factor-kappaB (NF-kappaB) activation. Expression of dominant-active H-Ras and p85 (a subunit of PI3K) increased MMP-9 activity, whereas dominant-negative forms of these molecules decreased the level of MMP-9. H-Ras did not increase MMP-9 in the presence of a PI3K inhibitor, LY294002, and a NF-kappaB inhibitor, SN50. Further studies showed that isoginkgetin regulated MMP-9 production via PI3K/Akt/NF-kappaB pathway, as evidenced by the findings that isoginkgetin inhibited activities of both Akt and NF-kappaB. PI3K/Akt is a well-known key pathway for cell invasion, and isoginkgetin inhibited HT1080 tumor cell invasion substantially. Isoginkgetin was also quite effective in inhibiting the activities of Akt and MMP-9 in MDA-MB-231 breast carcinomas and B16F10 melanoma. Moreover, isoginkgetin treatment resulted in marked decrease in invasion of these cells. In summary, PI3K/Akt is a major pathway for MMP-9 expression and isoginkgetin markedly decreased MMP-9 expression and invasion through inhibition of this pathway. This suggests that isoginkgetin could be a potential candidate as a therapeutic agent against tumor invasion.

A novel mechanism of tissue inhibitor of metalloproteinases-1 activation by interleukin-1 in primary human astrocytes

Reactive astrogliosis is the gliotic response to brain injury with activated astrocytes and microglia being the major effector cells. These cells secrete inflammatory cytokines, proteinases, and proteinase inhibitors that influence extracellular matrix (ECM) remodeling. In astrocytes, the expression of tissue inhibitor of metalloproteinases-1 (TIMP-1) is up-regulated by interleukin-1 (IL-1), which is a major neuroinflammatory cytokine. We report that IL-1 activates TIMP-1 expression via both the IKK/NF-kappaB and MEK3/6/p38/ATF-2 pathways in astrocytes. The activation of the TIMP-1 gene can be blocked by using pharmacological inhibitors, including BAY11-7082 and SB202190, overexpression of the dominant-negative inhibitor of NF-kappaB (IkappaBalphaSR), or by the knock-down of p65 subunit of NF-kappaB. Binding of activated NF-kappaB (p50/p65 heterodimer) and ATF-2 (homodimer) to two novel regulatory elements located -2.7 and -2.2 kb upstream of the TIMP-1 transcription start site, respectively, is required for full IL-1-responsiveness. Mutational analysis of these regulatory elements and their weak activity when linked to the minimal tk promoter suggest that cooperative binding is required to activate transcription. In contrast to astrocytes, we observed that TIMP-1 is expressed at lower levels in gliomas and is not regulated by IL-1. We provide evidence that the lack of TIMP-1 activation in gliomas results from either dysfunctional IKK/NF-kappaB or MEK3/6/p38/ATF-2 activation by IL-1. In summary, we propose a novel mechanism of TIMP-1 regulation, which ensures an increased supply of the inhibitor after brain injury, and limits ECM degradation. This mechanism does not function in gliomas, and may in part explain the increased invasiveness of glioma cells.

Rac upregulates tissue inhibitor of metalloproteinase-1 expression by redox-dependent activation of extracellular signal-regulated kinase signaling

The Rho-like GTPase Rac regulates distinct actin cytoskeleton changes required for adhesion, migration and invasion of cells. Tiam1 specifically activates Rac, and Rac has been shown to affect several signaling pathways in a partly cell-type-specific manner. Recently, we demonstrated that Rac activation inhibits Matrigel invasion of human carcinoma cells by transcriptional upregulation of tissue inhibitor of metalloproteinase-1. The purpose of the present study was to identify key mediators of Tiam1/Rac-induced tissue inhibitor of metalloproteinase-1 expression. Mutational analysis of the human tissue inhibitor of metalloproteinase-1 promoter revealed a major role for a distinct activating protein-1 site at -92/-86 and a minor role for an adjacent polyoma enhancer A3 site. Moreover, Rac activation induced the generation of reactive oxygen species and subsequent reactive oxygen species-dependent activation of extracellular signal-regulated kinase 1,2. In contrast, c-Jun N-terminal kinase and p38 mitogen-activated protein kinase activities were not affected. In line with this, Tiam1/Rac-induced tissue inhibitor of metalloproteinase-1 expression as well as Tiam1/Rac-induced binding of nuclear extracts to the activating protein-1 site at -92/-86 were inhibited by catalase and by specific inhibitors of the extracellular signal-related kinase-1,2 activators, mitogen-activated protein kinase kinase-1 and mitogen-activated protein kinase kinase-2 (PD098059, U0126). In conclusion, Rac-induced transcriptional upregulation of tissue inhibitor of metalloproteinase-1 is mediated by reactive oxygen species-dependent activation of extracellular signal-related kinase-1,2 and by transcription factors of the activating protein-1 family.

Potential mechanisms for astrocyte-TIMP-1 downregulation in chronic inflammatory diseases

The pathogenesis of many neurodegenerative disorders, including human immunodeficiency virus (HIV)-1 associated dementia, is exacerbated by an imbalance between matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs). In the context of disease, TIMP-1 has emerged as an important multifunctional protein capable of regulating inflammation. We previously reported differential TIMP-1 expression in acute versus chronic activation of astrocytes. This study investigates possible mechanisms underlying TIMP-1 downregulation in chronic neuroinflammation. We used interleukin (IL)-1beta as a model pro-inflammatory stimulus and measured TIMP-1 binding to extracellular matrix, cell death, receptor downregulation, TIMP-1 mRNA stability and transcriptional regulation in activated astrocytes. TIMP-1 remained localized to the cell body or was secreted into the cell supernatant. DNA fragmentation ELISA and MTT assay showed that prolonged IL-1beta activation of astrocytes induced significant astrocyte death. In acute and chronic IL-1beta-activated astrocytes, IL-1 receptor levels were not significantly different. TIMP-1 mRNA stability was measured in astrocytes and U87 astroglioma cells by real-time PCR, and TIMP-1 promoter activation was studied using TIMP-1-luciferase reporter constructs in transfected astrocytes. Our results indicated that TIMP-1 expression is regulated through multiple mechanisms. Transcriptional control and loss of mRNA stabilization are, however, the most likely primary contributors to chronic downregulation of TIMP-1. These data are important for unraveling the mechanisms underlying astrocyte responses during chronic neuroinflammation and have broader implications in other inflammatory diseases that involve MMP/TIMP imbalance.

p53 negatively regulates the expression of FAT10, a gene upregulated in various cancers

FAT10 is a member of the ubiquitin-like modifier family of proteins and has been implicated to play important roles in antigen presentation, cytokine response, apoptosis and mitosis. We have recently demonstrated the upregulation of FAT10 gene expression in 90% of hepatocellular carcinoma patients. Here, we identified and characterized the promoter of the FAT10 gene to elucidate the mechanism of FAT10 gene expression. Notably, we found that the 5' untranslated region (5'UTR), from the transcription start site to 15 bases before the translational start site, displays significant promoter activity. Regions upstream of the 5'UTR (from +26 to -1997) do not confer any promoter activity. Curiously, FAT10 promoter activity and expression is significantly repressed in KB3-1 and HepG2 cells, which have wild-type p53, than in p53-negative Hep3B cells. The role of p53 in regulating FAT10 expression was evident by the significant downregulation (P<0.05) of FAT10 mRNA expression and promoter activity when wild-type p53 was transfected into p53-null Hep3B cells. Conversely, inhibiting p53 expression through siRNA against p53 significantly enhanced FAT10 expression and promoter activity. p53 was found to bind in vivo to the 5' half consensus sequence of p53-binding site located at the FAT10 promoter. Hence, we propose that FAT10 is a downstream target of p53 and dysregulation of FAT10 expression in p53-defective cells could contribute to carcinogenesis.

Novel role of TGF-beta in differential astrocyte-TIMP-1 regulation: implications for HIV-1-dementia and neuroinflammation

Astrocyte production of tissue inhibitor of metalloproteinase (TIMP)-1 is important in central nervous system (CNS) homeostasis and inflammatory diseases such as HIV-1-associated dementia (HAD). TIMPs and matrix metalloproteinases (MMPs) regulate the remodeling of the extracellular matrix. An imbalance between TIMPs and MMPs is associated with many pathologic conditions. Our recently published studies uniquely demonstrate that HAD patients have reduced levels of TIMP-1 in the brain. Astrocyte-TIMP-1 expression is differentially regulated in acute and chronic inflammatory conditions. In this and the adjoining report (Gardner et al., 2006), we investigate the mechanisms that may be involved in differential TIMP-1 regulation. One mechanism for TIMP-1 downregulation is the production of anti-inflammatory molecules, which can activate signaling pathways during chronic inflammation. We investigated the contribution of transforming growth factor (TGF)-signaling in astrocyte-MMP/TIMP-1-astrocyte regulation. TGF-beta1 and beta2 levels were upregulated in HAD brain tissues. Co-stimulation of astrocytes with IL-1beta and TGF-beta mimicked the TIMP-1 downregulation observed with IL-1beta chronic activation. Measurement of astrocyte-MMP protein levels showed that TGF-beta combined with IL-1beta increased MMP-2 and decreased proMMP-1 expression compared to IL-1beta alone. We propose that one of the mechanisms involved in TIMP-1 downregulation may be through TGF-signaling in chronic immune activation. These studies show a novel extracellular regulatory loop in astrocyte-TIMP-1 regulation.

Tissue inhibitors of metalloproteinases-1 (TIMP-1) and -2(TIMP-2) are major serum factors that stimulate the TIMP-1 gene in human gingival fibroblasts

We demonstrate in this study that both TIMP-1 and TIMP-2 are major serum factors that stimulate the induction of TIMP-1 mRNA in quiescent human gingival fibroblasts (Gin-1 cells) at mid-G1 (6-9 h after serum stimulation) of the cell cycle, but not that of TIMP-2. When we chased the secretion of both TIMP proteins into culture medium containing 10% FCS freed of both TIMPs, TIMP-2 secretion rose to the level in 10% FCS after 24 h, but TIMP-1 secretion remained at a fairly low level even after 3 days, thus reflecting a contrastive difference in the induction of both TIMP mRNAs. The stimulating activity of TIMP-1 on the expression of the TIMP-1 gene switched over to inhibitory activity, when the TIMP-1 concentration in the culture medium exceeded about 30 ng/ml. The depletion of TIMP-1 and TIMP-2 from FCS affected remarkably the induction of c-jun and c-fos mRNAs, but not that of c-ets-1 mRNA. TIMP-1 and TIMP-2-dependent expression of AP-1 protein was further demonstrated by using nuclear extracts of Gin-1 cells in an electrophoretic mobility shift assay.

Proteasome blockade exerts an antifibrotic activity by coordinately down-regulating type I collagen and tissue inhibitor of metalloproteinase-1 and up-regulating metalloproteinase-1 production in human dermal fibroblasts

Tissue fibrosis results when dysregulation of extracellular matrix (ECM) turnover favors deposition of collagen and other ECM proteins over degradation. Fibrosis may then lead to organ dysfunction and pathology as observed in systemic sclerosis (SSc). In the present study, we investigated the antifibrotic properties of proteasome blockade. A dose- and time-dependent reduction in type-I collagen and tissue inhibitor of metalloproteinase-1 (TIMP-1) production was observed in normal fibroblasts exposed to proteasome inhibitors (PI). In the same culture conditions, metalloproteinase-1 (MMP-1) protein and the collagenolytic activity on type I collagen was increased. The steady-state mRNA levels of COL1A1, TIMP-1, and MMP-1 paralleled protein levels. These effects were dominant over the profibrotic properties of TGF-beta and were observed with fibroblasts generated from normal and SSc skin. PI decreased type I collagen mRNA levels with kinetics similar to those observed with DRB, a specific RNA polymerase II inhibitor, thus indicating transcriptional inhibition. Of interest, PI induced c-Jun phosphorylation and c-Jun nuclear accumulation. The specific N-terminal Jun-kinase inhibitor SP-600125 selectively abrogated c-Jun phosphorylation and, in a dose-dependent fashion, the up-regulated synthesis of MMP-1 induced by PI. Finally, PI did not affect fibroblast viability. Thus, the coordinated down-regulation of collagen and TIMP-1 and up-regulation of MMP-1 renders proteasome blockade an attractive strategy for treating conditions as SSc, characterized by excessive fibrosis.

TIMP-1 as candidate gene for embryo survival in two divergent lines selected for uterine capacity in rabbits

Selection on uterine capacity has been used in animal breeding as a way to improve the litter size. A divergent selection experiment for uterine capacity was performed in rabbits during ten generations. After the first generations of selection, large differences in number of implanted embryos were obtained between high and low lines. The major part of the differences between lines was due to embryo survival. A segregation analysis suggested the presence of a major gene affecting the reproductive traits. The objective of this work was to test the TIMP-1 gene as a candidate gene for embryo survival in rabbits since it stands up as a target for the investigation of reproductive problems in humans. We have analyzed the parental generation of a F2 cross which consists of 8 and 14 animals from the high and low uterine capacity lines, respectively. The rabbit TIMP-1 gene structure and sequence has been determined, including the proximal promoter region. Despite of the absence of polymorphism between lines in the screened regions (CDS, proximal promoter, exon 1, intron 1, and exon 2), a real-time RT-PCR quantification of the TIMP-1 mRNA in oviduct has shown significant differences between high and low lines at 62 hr of gestation, just when rabbit embryos are located in the oviduct, postulating TIMP-1 as an interesting candidate gene to be involved in the phenotypic differences between the two rabbit lines.

Phosphatidylinositol 3-kinase/Akt induced by erythropoietin renders the erythroid differentiation factor GATA-1 competent for TIMP-1 gene transactivation

The contribution of erythropoietin to the differentiation of the red blood cell lineage remains elusive, and the demonstration of a molecular link between erythropoietin and the transcription of genes associated with erythroid differentiation is lacking. In erythroid cells, expression of the tissue inhibitor of matrix metalloproteinase (TIMP-1) is strictly dependent on erythropoietin. We report here that erythropoietin regulates the transcription of the TIMP-1 gene upon binding to its receptor in erythroid cells by triggering the activation of phosphatidylinositol 3-kinase (PI3K)/Akt. We found that Akt directly phosphorylates the transcription factor GATA-1 at serine 310 and that this site-specific phosphorylation is required for the transcriptional activation of the TIMP-1 promoter. This chain of events can be recapitulated in nonerythroid cells by transfection of the implicated molecular partners, resulting in the expression of the normally silent endogenous TIMP-1 gene. Conversely, TIMP-1 secretion is profoundly decreased in erythroid cells from fetal livers of transgenic knock-in mice homozygous for a GATA(S310A) gene, which encodes a GATA-1 mutant that cannot be phosphorylated at Ser(310). Furthermore, retrovirus-mediated expression of GATA(S310A) into GATA-1(null)-derived embryonic stem cells decreases the rate of hemoglobinization by more than 50% compared to expressed wild-type GATA-1. These findings provide the first example of a chain of coupling mechanisms between the binding of erythropoietin to its receptor and GATA-1-dependent gene expression.

1alpha,25-dihydroxyvitamin D3 inhibits prostate cancer cell invasion via modulation of selective proteases

Inhibition of invasion and metastasis has become a new approach for treatment of advanced prostate cancer in which secondary hormone therapy has failed. Accumulating evidence indicates that 1alpha,25-dihydroxyvitamin D3 (1,25-VD) suppresses prostate cancer progression by inhibition of tumor growth and metastasis. However, the detailed mechanisms underlying these effects remain to be determined. Here, we used the in vitro cell invasion assay to demonstrate that 1,25-VD inhibits the invasive ability of human prostate cancer cell lines, LNCaP, PC-3 and DU 145. Three major groups of proteases, the matrix metalloproteinases (MMPs), the plasminogen activators (PAs) and the cathepsins (CPs), that are involved in tumor invasion were then examined for changes in activity and expression after 1,25-VD treatment. We found that 1,25-VD decreased MMP-9 and CPs, but not PAs activities, while it increased the activity of their counterparts, tissue inhibitors of metalloproteinase-1 (TIMP-1) and cathepsin inhibitors. Mechanistic studies showed that 1,25-VD did not suppress MMP-9 expression at the transcriptional level, but reduced its mRNA stability. In addition, 1,25-VD increased AP-1 complexes binding to TIMP-1 promoter, which contributed to the enhancement of TIMP-1 activity, and thus resulted in inhibition of MMP activity and tumor invasion. These findings support the idea that vitamin D-based therapies might be beneficial in the management of advanced prostate cancer, especially among patients who have higher MMP-9 and CPs activities.

Expression of matrix metalloproteinase (MMP)-2 and MMP-9 in breast cancer with a special reference to activator protein-2, HER2, and prognosis

PURPOSE

In the present study, we investigated the expression and prognostic value of matrix metalloproteinase (MMP)-2 and MMP-9 in breast cancer as well as their relation to transcription factor activator protein (AP)-2 and HER2 oncogene. The role of invasion and metastasis-promoting MMPs and their potential regulators, AP-2 and HER2, is currently still unclear in breast cancer.

EXPERIMENTAL DESIGN

MMP-2 and MMP-9 expressions were analyzed immunohistochemically in a large prospective series of 421 breast cancer patients diagnosed and treated between 1990 and 1995 at Kuopio University Hospital (Kuopio, Finland). The relation of MMP-2 and MMP-9 expressions to AP-2, HER2, clinicopathological data, and survival was investigated.

RESULTS

Both MMP-2 and MMP-9 were expressed in the cytoplasm of malignant and stromal cells. High expression of MMPs in carcinoma cells was related to small tumors (T1, stage I), whereas positive stromal expression of MMPs was associated with aggressive factors. High expression of MMP-2 and MMP-9 in carcinoma cells, but not in stromal cells, was related to high AP-2 expression. Positive stromal MMP-2 expression was associated with HER2 overexpression in the whole patient group and in the node-negative patient subgroup. Positive stromal MMP-9 expression was related to HER2 overexpression in estrogen receptor (ER)-positive disease. In the univariate survival analysis, positive stromal MMP-9 predicted shorter recurrence-free survival (RFS; P=0.0389) and breast cancer-related survival (BCRS; P=0.0081) in ER+ disease, especially in the subgroup of ER+ tumors of < or =2 cm in diameter (T1; P=0.0031 for RFS, and P=0.0089 for BCRS). High MMP-9 expression in cancer cells predicted longer RFS (P=0.0351) in the whole patient group. In the multivariate analysis of the whole patient group, the independent predictors of shorter RFS were reduced MMP-9 expression in carcinoma cells (P=0.0248), HER2 overexpression (P=0.0001), and advanced-stage disease (P=0.0002). Shorter BCRS was predicted by advanced-stage disease (P <0.0001).

CONCLUSIONS

Expression of MMP-2 and MMP-9 in breast cancer seems to be partly related to expression of AP-2 and HER2. Positive stromal MMP-9 expression predicts poor survival in the hormone-responsive small tumors, whereas MMP-9 expression in carcinoma cells favors survival. Evaluation of MMP-9 expression seems to add valuable information on breast cancer prognosis.

Farnesyltransferase inhibitor SCH-66336 downregulates secretion of matrix proteinases and inhibits carcinoma cell migration

The ras oncogenes are among those most frequently found in human cancers. Blocking Ras farnesylation is a promising strategy for arresting cancer growth. Ras activates several signaling pathways with key roles in cellular proliferation, invasion, metastasis and angiogenesis. Furthermore, proteolytic activities of matrix proteinases such as urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs) are regulated by Ras isoforms. Thus, we investigated the effects of SCH-66336, a farnesyltransferase inhibitor, on secretion of components of the plasminogen activation system as well as on the gelatinases MMP-2 and MMP-9, which play pivotal roles in matrix remodeling. SCH-66336 up to 5 microM did not significantly alter the viability of prostate (PC-3) and renal (Caki-1) cancer cells incubated in serum-depleted medium. SCH-66336 partly inhibited the processing of H-Ras, while levels of mature N-Ras and K-Ras remained unaffected. Under these noncytotoxic conditions, uPA and tPA levels were lowered in culture medium but raised in cell lysates, suggesting inhibition of trafficking pathways. In contrast, SCH-66336 had no effect on uPAR expression or on secreted PAI-1 levels. As expected, the reduction of uPA and tPA activities by SCH-66336 inhibited the conversion of plasminogen to plasmin by about 25% in PC-3 cells. SCH-66336 also inhibited the levels of secreted pro-MMP-2 and pro-MMP-9 as well as the release of their inhibitors TIMP-1 and TIMP-2. SCH-66336 decreased both the adhesion and even more so the migration of PC-3 cells on gelatin. Thus, SCH-66336 inhibited farnesylation in both cancer cell types, and H-Ras functions should be reduced by the drug. In addition, the lower levels of secreted proteinases in the presence of SCH-66336 suggest that reduced matrix remodeling and cell migration should occur in treated tumors.

Differential effects of histone deacetylase inhibitors on phorbol ester- and TGF-β1 induced murine tissue inhibitor of metalloproteinases-1 gene expression

Expression of the tissue inhibitor of metalloproteinases-1 (Timp-1) gene can be induced by either phorbol myristate acetate (PMA) or transforming growth factor beta1 (TGF-beta1), although the signalling pathways involved are not clearly defined. Canonically, histone deacetylase inhibitors (HDACi) such as trichostatin A (TSA) or sodium butyrate (NaB) increase total cellular histone acetylation and activate expression of susceptible genes. Remarkably, PMA and TGF-beta1 stimulation of Timp-1 show a differential response to TSA or NaB. TSA or NaB potentiate PMA-induced Timp-1 expression but repress TGF-beta1-induced Timp-1 expression. The repression of TGF-beta1-induced Timp-1 by TSA was maximal at 5 ng.mL(-1), while for the superinduction of PMA-induced Timp-1 expression, the maximal dose is > 500 ng x mL(-1) TSA. A further HDACi, valproic acid, did not block TGF-beta1-induced Timp-1 expression, demonstrating that different HDACs impact on the induction of Timp-1. For either PMA or TGF-beta1 to induce Timp-1 expression, new protein synthesis is required, and the induction of AP-1 factors closely precedes that of Timp-1. The effects of the HDACi can be reiterated in transient transfection using Timp-1 promoter constructs. Mutation or deletion of the AP-1 motif (-59/-53) in the Timp-1 promoter diminishes PMA-induction of reporter constructs, however, the further addition of TSA still superinduces the reporter. In c-Jun-/- cells, PMA still stimulates Timp-1 expression, but TSA superinduction is lost. Transfection of a series of Timp-1 promoter constructs identified three regions through which TSA superinduces PMA-induced Timp-1 and we have demonstrated specific protein binding to two of these regions which contain either an avian erythroblastosis virus E26 (v-ets) oncogene homologue (Ets) or Sp1 binding motif.

Common dihydrofolate reductase 19-base pair deletion allele: a novel risk factor for preterm delivery

BACKGROUND

Folate is critical for cell division, a major feature of in utero development. Dihydrofolate reductase (DHFR) is required to convert the folic acid used in supplements and for food fortification and the dihydrofolate produced by thymidylate synthase during DNA synthesis to the reduced folate forms used by the cell.

OBJECTIVE

We aimed to determine whether a common, recently discovered deletion polymorphism in the DHFR gene is a risk factor for preterm delivery or low birth weight.

DESIGN

We studied 324 pregnant women from Camden, NJ. Folate intake was computed from folate supplement intake plus the mean of two 24-h recalls completed during the course of pregnancy. Genomic DNA was extracted from the women's leukocytes and genotyped.

RESULTS

Women with a deletion allele had a significantly greater risk of preterm delivery [adjusted odds ratio (AOR): 3.0; 95% CI: 1.0, 8.8; P < 0.05] than did those without a deletion allele. Women with both a DHFR deletion allele and low folate intake (<400 microg/d from diet plus supplements) had a significantly greater risk of preterm delivery (AOR: 5.5; 95% CI: 1.5, 20.4; P = 0.01) and a significantly greater risk of having an infant with a low birth weight (AOR: 8.3; 95% CI: 1.8, 38.6; P = 0.01) than did women without a deletion allele and with a folate intake >/=400 microg/d.

CONCLUSIONS

The DHFR 19-base pair deletion allele may be a risk factor for preterm delivery. In the presence of low dietary folate, the allele may also be a risk factor for low birth weight. This may be a gene-environment interaction.

Induction by IL-1β of Tissue Inhibitor of Metalloproteinase-1 in Human Orbital Fibroblasts: Modulation of Gene Promoter Activity by IL-4 and IFN-γ

Thyroid-associated ophthalmopathy (TAO), an autoimmune component of Graves' disease, is associated with profound connective tissue remodeling and fibrosis that appear to involve the selective activation of orbital fibroblasts. Accumulation of extracellular matrix molecules is a hallmark of this process. Here we report that orbital fibroblasts treated with IL-1beta express high levels of tissue inhibitor of metalloproteinase-1 (TIMP-1), an important modulator of matrix metalloproteinase activity. These high levels are associated with increased TIMP-1 activity. The induction is mediated at the pretranslational level and involves activating the TIMP-1 gene promoter. IL-1beta activates the ERK 1/2 pathway in these fibroblasts and interrupting this signaling either with PD98059, a chemical inhibitor of MEK, or by transfecting cells with a dominant negative ERK 1 plasmid results in the attenuation of TIMP-1 induction. Surprisingly, treatment with IL-4 or IFN-gamma could also block the IL-1beta induction by attenuating TIMP-1 gene promoter activity. These findings suggest that TIMP-1 expression in orbital fibroblasts following activation with IL-1beta could represent an important therapeutic target for modifying the proteolytic environment. This might alter the natural course of tissue remodeling in TAO.

Chromatin immunoprecipitation (ChIP) on chip experiments uncover a widespread distribution of NF-Y binding CCAAT sites outside of core promoters

The CCAAT box is a prototypical promoter element, almost invariably found between -60 and -100 upstream of the major transcription start site. It is bound and activated by the histone fold trimer NF-Y. We performed chromatin immunoprecipitation (ChIP) on chip experiments on two different CpG islands arrays using chromatin from hepatic HepG2 and pre-B cell leukemia NALM-6 cell lines, with different protocols of probe preparation and labeling. We analyzed and classified 239 known or predicted targets; we validated several by conventional ChIPs with anti-YB and anti-YC antibodies, in vitro EMSAs, and ChIP scanning. The importance of NF-Y binding for gene expression was verified by the use of a dominant negative NF-YA mutant. All but four genes are new NF-Y targets, falling into different functional categories. This analysis reinforces the notion that NF-Y is an important regulator of cell growth, and novel unexpected findings emerged from this unbiased approach. (i) A remarkable proportion of NF-Y targets, 40%, are complex transcriptional units composed of divergent, convergent, and tandem promoters. (ii) 40-50% of NF-Y sites are not in core promoters but are in introns or at distant 3' or 5' locations. The abundance of "unorthodox" CCAAT positions highlights an unexpected complexity of the NF-Y-mediated transcriptional network.

Inhibition of Cytotrophoblastic (JEG-3) Cell Invasion by Interleukin 12 Involves an Interferon γ-mediated Pathway

Trophoblast invasion, like tumor invasion, shares common biochemical mechanisms. However, in contrast to tumor invasion of a host tissue, trophoblastic invasion during implantation is strictly regulated, temporospatially. Factors responsible for these important regulatory processes are presently unknown; however, studies indicate that cytokines and growth factors represent in the peri-implantation uterine milieu as the possible candidates. In this study we investigated the role of interleukin (IL) 12 in regulating trophoblast invasion and the expression of trophoblast proteases (matrix metalloprotease (MMP)-2, MMP-9, and urokinase-type plasminogen activators) and their inhibitors (tissue inhibitors of metalloprotease (TIMP) 1, TIMP-2, and plasminogen activator inhibitor (PAI)-1) using an in vitro tissue culture system of human choriocarcinoma cell line JEG-3. Our major findings show an anti-invasive role of IL-12, associated with an inhibitory effect on the proteases but with an opposite up-regulating influence on the protease inhibitor, TIMP-1, whereas TIMP-2 and plasminogen activator inhibitor 1 remained unaltered. Stimulation of JEG-3 cells with IL-12 also induced interferon (IFN)-gamma production, which when neutralized using a monoclonal anti-IFN-gamma antibody, F12, abrogates its ability to down-regulate the MMPs. IL-12 also mediates an IFN-gamma-dependent up-regulation of E-cadherin, thereby implying that alteration in cell-cell adhesion besides regulating the proteases and the inhibitors possibly contributes to the observed anti-invasive role of this cytokine. TIMP-1, although stimulated by IL-12, was found to be unaltered by antibody F12, thereby implying a possibility of an IL-12-dependent-IFN-gamma independent regulation. These findings thereby suggest an important role of IL-12 in modulation of trophoblast proteases and their inhibitors besides regulating cell-cell interactions and invasion during implantation, with far reaching possibilities for understanding the mechanism(s) and regulations of invasion and metastasis.

Sp1-dependent regulation of the tissue inhibitor of metalloproteinases-1 promoter

Extracellular matrix (ECM) remodeling is involved in many cellular properties such as division, migration, differentiation, and death. The turnover of ECM is regulated by matrix metalloproteinases (MMPs) and the MMPs are inhibited by the tissue inhibitors of metalloproteinases (TIMPs). In this study, the transcriptional regulation of the TIMP-1 promoter was investigated. The 5'-deletion assay showed that the region between -1,200 and -1,101 was responsible for the TIMP-1 promoter activity. The mutations of the two Sp1 sites in this region reduced the transcription activity. In addition, the co-transfection with antisense Sp1 oligonucleotide decreased the promoter activity, suggesting that the transcription of the TIMP-1 promoter is mediated by Sp1. Previously, it was reported that the TIMP-1 expression was enhanced under hypoxia. Therefore, the TIMP-1 promoter activity was investigated with or without cobalt ion, which elicits the same physiological effect as hypoxia. The results showed that the TIMP-1 promoter was induced in the presence of cobalt ion and that the promoter activity was regulated by Sp1 as well as HIF-1. Therefore, this study suggests that Sp1 is involved in the regulation of the TIMP-1 promoter in the presence of cobalt ion as well as in the basal level transcription.

Global gene expression profiling in interleukin-12-induced activation of CD8(+) cytotoxic T lymphocytes against mouse mammary Carcinoma

Interleukin-12 (IL-12) is a critical cytokine representing the link between the cellular and humoral branches of host immune defense apparatus. IL-12-induced cytotoxic lymphocyte (CTL) development is a central mechanism in immune responses against intracellular infectious agents as well as malignant growth. However, the molecular basis of tumor-specific CTL responses mediated by IL-12 remains poorly defined. In this study, we addressed this issue in a comprehensive manner to probe into IL-12-induced anti-tumor responses by global gene expression profiling of mRNA expression in CD8(+) T cells in a transplantable syngeneic mouse mammary carcinoma model treated or not with recombinant IL-12. A strong tumor regression was induced by the IL-12 treatment. An introspection of differential gene expression at an early stage of the IL-12-initiated CTL activation reveals interesting genes and molecular pathways that may account for the marked tumor regression, and is likely to provide a rich source of potential targets for further research and development of effective therapeutic modalities.

New 19 bp deletion polymorphism in intron-1 of dihydrofolate reductase (DHFR): a risk factor for spina bifida acting in mothers during pregnancy?

Up to 72% of spina bifida cystica (SB) is preventable by maternal periconceptual folic acid supplementation. The C677T allele of the methylenetetrahydrofolate reductase (MTHFR) gene and some other functional polymorphisms are risk factors for SB in some populations. However, despite extensive study, the genetic risk factors for SB are incompletely understood. Polymorphic alleles that diminish bioavailability of reduced folate in the mother during pregnancy could contribute to SB in her fetus, acting in the mother as teratogenic alleles. We recently discovered a polymorphic 19 bp deletion allele (frequency 0.45) within intron-1 of dihydrofolate reductase (DHFR) that is a good candidate for such a genetic factor. Since there is precedence for intron-1 regulatory elements and the deletion allele removes a potential Sp1 transcription factor binding site, we hypothesized that the deletion allele could be functional and act in SB mothers to increase the risk of SB in her fetus. We found that homozygosity for this deletion allele was significantly more frequent in SB mothers, but not in SB fathers or patients, compared with controls and was associated with a significantly increased odds ratio (OR) (2.035) of being an SB mother compared with other genotypes. Genotype distribution obeyed the constraints of Hardy-Weinberg equilibrium in controls, SB patients and fathers, but not in SB mothers. If confirmed, these findings could lead to improved forms of folate supplementation for pregnancy. About half of dietary folates and all of folic acid supplements must be reduced by DHFR to be available for mother and fetus. Reduced folates could be preferable for supplements during pregnancy to prevent SB.

Induction of cell death in activated hepatic stellate cells by targeted gene expression of the thymidine kinase/ganciclovir system

Liver fibrosis is the result from a relative imbalance between synthesis and degradation of matrix proteins. Following liver injury of any etiology, hepatic stellate cells undergo a response known as activation, which is the transition of quiescent cells into proliferative, fibrogenic, and contractile myofibroblasts. Upon this cellular transdifferentiation the effector cell becomes the major source of fibrillar and non-fibrillar matrix proteins resulting in excessive scar formation and cirrhosis, the end stage of fibrosis. Concomitant with progressive liver fibrosis, the tissue inhibitor of metalloproteinases-1 (TIMP-1) is strongly activated in hepatic stellate cells. We have developed a recombinant replication-defective adenovirus in which the TIMP-1 promoter is coupled to the herpes simplex virus thymidine kinase gene rendering activated hepatic stellate cells susceptible to ganciclovir. This novel targeted suicide gene approach was validated in a culture model considered to reflect an accelerated time course of the cellular and molecular events that occur during liver fibrosis. We demonstrate that transfer of the suicide gene to culture-activated hepatic stellate cells results in a strong expression of the respective transgene as assessed by Northern blot and Western blot analyses. The enzyme catalyzed the proper conversion of its prodrug subsequently initiating programmed cell death as estimated by caspase-3 assay and Annexin V-Fluos staining. Altogether, these results indicate that induction of programmed cell death is a promising approach to eliminate fibrogenic HSC.

Matrix Metalloproteinase 9 Expression is Coordinately Modulated by the KRE-M9 and 12-O-Tetradecanoyl-Phorbol-13-Acetate Responsive Elements

To investigate the pathophysiologic role of matrix metalloproteinase 9 (MMP-9), we analyzed the mechanism of its transcriptional regulation in keratinocytes and in HT1080 fibrosarcoma cells in culture. The KRE-M9 element, which is located between the 12-O-tetradecanoyl-phorbol-13-acetate responsive element (TRE) and the transcription initiation site in the MMP-9 promoter, is essential for MMP-9 transcription in the absence of the TRE. The KRE-M9 binding protein, however, is shown to be a repressor of transcription rather than an activator; we found several times higher transcriptional activity when the KRE-M9 element was mutated. In contrast, activator protein 1 proteins (AP-1) are shown to activate transcription of MMP-9 by binding to the TRE, which is located adjacent to the KRE-M9 element. Moreover, we found that the KRE-M9 binding protein could serve as a differentiation repressing factor 1 (DRF-1) as shown by the decrease in levels of this protein with differentiation. In addition, the TRE binding protein is able to bind to the KRE-M9 to some extent. These results indicate that the coordinated modulation of MMP-9 transcription via the TRE and the KRE-M9 elements is important in epidermal and mesenchymal tissues. Our findings could facilitate consideration of the molecular mechanism in a variety of pathophysiologic conditions with which MMP-9 is involved.

CSRP2, TIMP-1, and SM22alpha promoter fragments direct hepatic stellate cell-specific transgene expression in vitro, but not in vivo

BACKGROUND/AIMS

The activation of hepatic stellate cells (HSC) and their transdifferentiation into myofibroblasts (MFB) is the key step for development of liver fibrosis. Over the past several years, significant progress has been made in the understanding of the critical pathways involved incells undergoing activation. Cellular activation in the course of transdifferentiation involves, among other biochemical modifications, functionally relevant changes in the control of gene expression. These include the up-regulation of transcription factors, different extracellular matrix proteins, cell adhesion molecules, smooth muscle specific genes, and proteins involved in matrix remodelling, or cytoskeletal organization. The corresponding regulatory elements of these genes have afforded us the opportunity to express transgenes with antifibrotic potential in a cell type- and/or transdifferentiation-dependent manner.

METHODS

In the present study, we have tested several promoters for their ability to mediate cell-specific expression, including those for CSRP2, SM22alpha, and TIMP-1 (CSRP2, gene encoding the LIM domain protein CRP2; SM22alpha, smooth muscle-specific gene encoding a 22-kDa protein; TIMP-1, gene encoding the tissue inhibitor of metalloproteinases-1), which in liver are specifically expressed in HSC or become strongly activated during the acute remodelling into MFB. We constructed adenoviral reporter vectors in which relevant portions of the promoters were fused to the green fluorescent protein.

RESULTS AND CONCLUSION

Our experiments demonstrate that each of these promoters is sufficient to achieve strong or partially selective expression in vitro but none is able to direct a specific or inducible expression of transgenes in HSC/MFB in vivo.

Identification of cJun-responsive genes in Rat-1a cells using multiple techniques: increased expression of stathmin is necessary for cJun-mediated anchorage-independent growth

cJun is a major component of the transcription factor AP-1 and mediates a diverse set of biologic properties including proliferation, differentiation, and apoptosis. To identify cJun-responsive genes, we inducibly expressed cJun in Rat-1a cells and observed two distinct phenotypes: changes in cellular morphology with adherent growth and anchorage-independent growth. The biologic effects of cJun were entirely reversible demonstrating that they require the continued presence of cJun. To determine the genes, which mediate the biologic effects of cJun, we employed multiple methods including differential gene analysis, suppression subtractive hybridization, and cDNA microarrays. We identified 38 cJun-responsive genes including three uncharacterized genes under adherent and/or nonadherent conditions. Half of the known 36 genes were cytoskeleton- and adhesion-related genes, suggesting a major role of cJun in the regulation of the genes related to cell morphology. As proof of the principle that this approach could identify genes whose upregulation was necessary for nonadherent growth, we investigated one gene, stathmin whose upregulation by cJun was observed only under these conditions. Although overexpression of stathmin did not result in nonadherent growth, inhibition of stathmin protein expression by antisense oligonucleotides in cJun-induced Rat-1a cells prevented nonadherent growth. These results suggest that stathmin plays an essential role in anchorage-independent growth by cJun and may be a potential target for specific inhibitors for AP-1-dependent processes involved in carcinogenesis.

The comparative role of activator protein 1 and Smad factors in the regulation of Timp-1 and MMP-1 gene expression by transforming growth factor-beta 1

The balance between matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), is pivotal in the remodeling of extracellular matrix. TGF-beta has profound effects on extracellular matrix homeostasis, in part via its ability to alter this balance at the level of gene expression. The intracellular signaling pathways by which TGF-beta mediates its actions include the Smad pathway, specific to the TGF-beta superfamily, but also, for example, mitogen-activated protein kinase pathways; furthermore, cross-talk between the Smads and other signaling pathways modifies the TGF-beta response. The reciprocal effect of TGF-beta on the expression of Timp-1 and MMP-1 supports its role in matrix anabolism, yet the mechanisms by which TGF-beta induces Timp-1 and represses induced MMP-1 have remained opaque. Here, we (i) investigate the mechanism(s) by which TGF-beta1 induces expression of the Timp-1 gene and (ii) compare this with TGF-beta1 repression of phorbol ester-induced MMP-1 expression. We report that the promoter-proximal activator protein 1 (AP1) site is essential for the response of both Timp-1 and MMP-1 to TGF-beta (induction and repression, respectively). c-Fos, JunD, and c-Jun are essential for the induction of Timp-1 gene expression by TGF-beta1, but these AP1 factors transactivate equally well from both Timp-1 and MMP-1 AP1 sites. Smad-containing complexes do not interact with the Timp-1 AP1 site, and overexpression of Smads does not substitute or potentiate the induction of the gene by TGF-beta1; furthermore, Timp-1 is still induced by TGF-beta1 in Smad knockout cell lines, although to varying extents. In contrast, Smads do interact with the MMP-1 AP1 site and mediate repression of induced MMP-1 gene expression by TGF-beta1.