Basal expression of the gene (TIMP) encoding the murine tissue inhibitor of metalloproteinases is mediated through AP1- and CCAAT-binding factors

Dill Extract Preserves Dermal Elastic Fiber Network and Functionality: Implication of Elafin

INTRODUCTION

Elastic skin fibers lose their mechanical properties during aging due to enzymatic degradation, lack of maturation, or posttranslational modifications. Dill extract has been observed to increase elastin protein expression and maturation in a 3D skin model, to improve mechanical properties of the skin, to increase elastin protein expression in vascular smooth muscle cells, to preserve aortic elastic lamella, and to prevent glycation.

OBJECTIVE

The aim of the study was to highlight dill actions on elastin fibers during aging thanks to elastase digestion model and the underlying mechanism.

METHODS

In this study, elastic fibers produced by dermal fibroblasts in 2D culture model were injured by elastase, and we observed the action of dill extract on elastic network by elastin immunofluorescence. Then action of dill extract was examined on mice skin by injuring elastin fibers by intradermal injection of elastase. Then elastin fibers were observed by second harmonic generation microscopy, and their functionality was evaluated by oscillatory shear stress tests. In order to understand mechanism by which dill acted on elastin fibers, enzymatic tests and real-time qPCR on cultured fibroblasts were performed.

RESULTS

We evidence in vitro that dill extract is able to prevent elastin from elastase digestion. And we confirm in vivo that dill extract treatment prevents elastase digestion, allowing preservation of the cutaneous elastic network in mice and preservation of the cutaneous elastic properties. Although dill extract does not directly inhibit elastase activity, our results show that dill extract treatment increases mRNA expression of the endogenous inhibitor of elastase, elafin.

CONCLUSION

Dill extract can thus be used to counteract the negative effects of elastase on the cutaneous elastic fiber network through modulation of PI3 gene expression.

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.

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.

A sequence-selective single-strand DNA-binding protein regulates basal transcription of the murine tissue inhibitor of metalloproteinases-1 (Timp-1) gene

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is important in maintaining the extracellular proteolytic balance during tissue remodeling processes. To allow homeostatic tissue turnover, the murine Timp-1 gene is expressed by most cells at a low basal level, and during acute remodeling its transcription is activated by a variety of stimuli. A non-consensus AP-1-binding site (5'-TGAGTAA-3') that is conserved in mammalian timp-1 genes is a critical element in basal and serum-stimulated transcription. We show here that each strand of this unusual AP-1 site binds a distinct single-stranded DNA-binding protein, although neither strand from a perfect consensus AP-1 site from the human collagenase gene shows similar binding. One of the single-strand binding factors, which we term ssT1, binds to a second upstream Timp-1 region between nucleotides -115 and -100. Deletion analysis demonstrated that this region is important in basal but not serum-inducible transcription. The ssT1 factor was 52-54 kDa by UV cross-linking of electrophoretic mobility shift assays and Southwestern blot analysis. Its binding to DNA shows sequence selectivity rather than specificity, with 5'-CT/ATTN((4-6))ATC-3' as a favored motif. Multiple ssT1-like activities were found in nuclear extracts from mouse fibroblasts and rat liver and testis, suggesting that these factors may regulate basal Timp-1 transcription in a tissue-specific fashion.

Altered balance between matrix metalloproteinases and their inhibitors in experimental biliary fibrosis

A rat model of common bile duct ligation (BDL)-induced hepatic fibrosis was used to assess the expression and activities of collagen-degrading proteinases and their inhibitors during the progression of fibrosis. Expression of four members of the matrix metalloproteinase (MMP) family (MMP-2/gelatinase A, MMP-3, MMP-9/gelatinase B, and MMP-13) and three tissue inhibitors of metalloproteinases-1, -2, and -3 (TIMP-1, TIMP-2, and TIMP-3) were evaluated by Northern blot analysis of RNA from liver tissue isolated at 0, 2, 5, 10, 20, and 30 days after either a BDL or sham operation. In addition, we analyzed free gelatinase and TIMP activities by zymography and reverse zymography, respectively. We found that the proteolytic activities of MMP-2 and MMP-9 increased by 2 days after ligation, reached maximal levels at day 10, and remained high through the study period, whereas the gelatinolytic activities in plasma were unchanged. The increase in gelatinase activities was accompanied by an increase in the TIMP mRNA transcripts. TIMP-1 transcripts appeared at day 2, increased until day 10, and remained elevated throughout the study period. TIMP-2 and TIMP-3 transcripts become detectable on day 10 and remained stable afterwards. No corresponding increase in TIMP protein activity was detected by reverse zymography. This appears to result from the formation of TIMP/MMP complexes. These findings indicate a likely surplus in the BDL model of fibrosis of free gelatinases as compared with the TIMPs. Thus, excessive TIMP production is not a sufficient explanation for the observed extracellular matrix accumulation, but complex changes in the local MMP/TIMP balance may underlie the pathomechanisms of fibrosis.

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

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

Repression of the 5-lipoxygenase gene by c-myb overexpression in differentiated HL-60 cells

This paper reports on the involvement of c-MYB in the regulation of 5-lipoxygenase gene expression during differentiation of human HL-60 cells. We demonstrate that c-MYB binds the 5-lipoxygenase promoter in undifferentiated cells but not in DMSO-differentiated cells. Also, we show that overexpression of c-myb cDNA in differentiated HL-60 cells represses the 5-lipoxygenase gene expression.

Angiotensin II induces TIMP-1 production in rat heart endothelial cells

Angiotensin II (AII) was found to upregulate tissue inhibitor of metalloproteineses-1 (TIMP-1) gene expression in rat heart endothelial cells in a dose and time-dependent manner. The maximal stimulation of TIMP-1 mRNA was achieved by 2 h after the addition of AII. This effect was blocked by losartan, an AT1 receptor antagonist and by calphostin C, a protein kinase C inhibitor. Addition of cycloheximide superinduced and actinomycin D abolished the induction. These results suggest that AII stimulates TIMP-1 production by a protein kinase C dependent pathway which is dependent upon de novo RNA synthesis. Immunoprecipitation experiment showed an enhanced band of 28 kDa from the conditioned medium of AII-treated cultures. Immunoblot analysis revealed that TIMP-1 was detectable in the conditioned medium 4 h after AII stimulation. Since endothelial cells line the blood vessels and sense the rise in AII associated with hypertension, the TIMP-1 released by these cells may provide an initial trigger leading to cardiac fibrosis in angiotensin-renin dependent hypertension.

The CD95 (APO-1/Fas) receptor activates NF-kappaB independently of its cytotoxic function

Engagement of the CD95 (APO-1/Fas) receptor induces apoptosis in a variety of cell types. However, the nature of the cytotoxic signal and the intermediate messenger molecules remain to be elucidated. In an effort to understand CD95-mediated signaling, we assessed possible changes in the DNA binding activity of NF-kappaB as a result of CD95 engagement in various tumor cells. By performing electrophoresis mobility shift assays, we show that CD95 can stimulate the DNA binding activity of NF-kappaB in a variety of cells, irrespective of their sensitivity or resistance to CD95-mediated cytotoxicity. Moreover, deletion of 37 carboxyl-terminal residues from the cytoplasmic domain of CD95, which abrogates CD95-mediated apoptosis, only marginally affects NF-kappaB activation. Taken together, these observations indicate that CD95 has a function that involves activation of NF-kappaB and that appears to be unrelated to its role as an inducer of apoptotic cell death.

Interleukin-1 beta induction of tissue inhibitor of metalloproteinase (TIMP-1) is functionally antagonized by prostaglandin E2 in human synovial fibroblasts

Elevated levels of tissue inhibitor of metalloproteases-1 (TIMP-1) have been demonstrated in inflamed synovial membranes, and it is believed that the inhibitor may play a critical role in the regulation of connective tissue degradation. The present study was undertaken to define the cellular mechanism of action of the inflammatory mediators, interleukin-1 beta (IL-1 beta) and prostaglandin E2 (PGE2), in the control of TIMP-1 synthesis and expression in human synovial fibroblasts. Recombinant human IL-1 beta induced a time- and dose-dependent saturable response in terms of TIMP-1 mRNA expression (effective concentration for 50% maximal response, EC50 = 31.5 +/- 3.3 pg/ml) and protein synthesis (EC50 = 30 +/- 3.3 pg/ml). The protein kinase C (PKC) inhibitors, H-7, staurosporine, and calphostin C, reversed the rhIL-1 beta induction of TIMP-1 mRNA. PGE2 also inhibited rhIL-1 beta-stimulated TIMP-1 mRNA expression and protein secretion in a dose-dependent fashion. The concentration of PGE2 necessary to block 50% of rhIL-1 beta-stimulated TIMP-1 secretion, IC50, was 1.93 ng/ml (4.89 nM). Forskolin, and other stable derivatives of cAMP, mimicked, to a large extent, the effects of PGE2. The phorbol ester, PMA, up-regulated considerably the mRNA expression of TIMP-1 but had no effect on protein production. Calphostin C substantially reduced PMA-activated TIMP-1 expression. Staurosporine, calphostin C, H-7, and substances that elevate cellular levels of cAMP, like PGE2, also reduced basal expression and synthesis of TIMP-1. Taken together, the data suggest that PKA and C may mediate opposing effects in terms of TIMP-1 expression and secretion in human synovial fibroblasts.

Characterization of the promoter of the gene encoding human tissue inhibitor of metalloproteinases-2 (TIMP-2)

Tissue inhibitors of metalloproteinases (TIMPs) are multifunctional proteins that control the proteolytic activity of matrix metalloproteinases (MMPs). We report here the cloning and characterization of a 2.5-kb genomic fragment of the human timp-2 gene that includes 519 bp of the 5' flanking region, the first coding exon (432-bp) and part of the first intron. The 5' flanking region has several features of housekeeping genes. It has a high G-C content and is included in a typical CpG island. It also contains a TATA-like element (AATAAAA) located 23 to 37-bp upstream from a cluster of transcription start points (tsp), several Sp1 and one AP-2 motifs, and an AP-1 consensus sequence located at position -590 to -583 from the start codon. When inserted upstream from a promoterless luciferase-encoding gene, a 715-bp fragment of this 5'-flanking sequence behaved as a promoter in transiently transfected NIH3T3 and Rat-1 fibroblasts. The effect of deletions of the promoter suggested the presence of a negative control element located between positions -661 and -575. This element includes the AP-1 consensus sequence. However, treatment with phorbol did not change activity in transfected cells and did not change the timp-2 mRNA content of human HT1080 fibrosarcoma cells. A comparison with the promoter of murine timp-1 revealed several differences consistent with the fact that timp-1 and timp-2 are differentially regulated.

Tissue inhibitor of metalloproteinases (TIMP, aka EPA): structure, control of expression and biological functions

The TIMPs play an important role in regulating the activity of the secreted metalloproteinases (collagenases, stromelysins, gelatinases). Two different TIMPS have been well characterized, each capable of inhibiting all tested eukaryotic metalloproteinases but showing specific binding to a particular gelatinase at a site distinct from the active site. They influence the activation of the prometalloproteinase and act to modulate proteolysis of extracellular matrix, notably during tissue remodeling and inflammatory processes. On certain cell types, they can exhibit growth factor-like activity, and they can inhibit the tumorigenic and metastatic phenotype of cancer cells.