Human stromelysin gene promoter activity is modulated by transcription factor ZBP-89

Interleukin-1β triggers matrix metalloprotease-3 expression through p65/RelA activation in melanoma cells

Melanoma shows highly aggressive behavior (i.e., local invasion and metastasis). Matrix metalloprotease-3 (MMP-3), a zinc-dependent endopeptidase, degrades several extracellular substrates and contributes to local invasion by creating a microenvironment suitable for tumor development. Here, we report that interleukin-1β (IL-1β) triggers the MMP-3 expression in canine melanoma cells. The activity of MMP-3 in the culture supernatant was increased in IL-1β-treated melanoma cells. IL-1β time- and dose-dependently provoked the mRNA expression of MMP-3. IL-1β induced the migration of melanoma cells; however, this migration was attenuated by UK356618, an MMP-3 inhibitor. When the cells were treated with the nuclear factor-κB (NF-κB) inhibitor TPCA-1, the inhibition of MMP-3 expression was observed. In IL-1β-treated cells, the phosphorylation both of p65/RelA and p105 was detected, indicating NF-κB pathway activation. In p65/RelA-depleted melanoma cells, IL-1β-mediated mRNA expression of MMP-3 was inhibited, whereas this reduction was not observed in p105-depleted cells. These findings suggest that MMP-3 expression in melanoma cells is regulated through IL-1β-mediated p65/RelA activation, which is involved in melanoma cell migration.

Matrix metalloproteinase 3 and 9 as genetic biomarkers for the occurrence of cardiovascular complications in coronary artery disease: a prospective cohort study

BACKGROUND

Matrix metalloproteinases (MMPs) are widely expressed in atherosclerosis lesions. The disequilibrium of MMPs driving to an overexpression or a lack of its level can be influenced by genetic variations. MMP-3 and MMP-9 may be affected by specific polymorphisms like - 1612 5 A/6A and the - 1562 C/T respectively. We aim in the present study to investigate prospectively the association between the - 1612 5 A/6A MMP-3 and - 1562 C/T MMP-9 polymorphisms and clinical outcomes in patients with coronary artery disease (CAD). This study is elaborated to reveal whether one of these polymorphisms is a probable predictor of cardiovascular complications in this CAD cohort.

METHODS AND RESULTS

A total of 168 patients with CAD were prospectively followed up over a period of 5 years. Genotypes for the MMP-3 (-1612 5 A/6A) and MMP-9 (-1562 C/T) polymorphisms were performed using PCR-RFLP. Their levels were measured by ELISA in Sandwich test during the follow-up period, 39 cardiovascular outcomes occurred with 21 repeat targets for revascularization, 3 patients with Myocardial infarction, 8 for heart failure, 5 for Stroke and 2 for cardiovascular mortality. The MMP-3 5 A/6A polymorphism was related to the disease on the contrary of the MMP-9 -1562 C/T. Patients carrying the 5 A allele had a higher level of MMP-3 level and those who carried the 6 A allele had lower level (p = 0.04). After applied multivariable Cox-hazard models we revealed that the 6 A allele is independently associated to the disease complication. Kaplan-Meier survival test revealed that individuals having the 6 A allele had a lower survival rate than those with the 5 A allele (p = 0.04).

CONCLUSION

Our study suggests the disruption of the MMP-3 level may be due to the existence of the polymorphism - 1612 residing in its promoter region. MMP-3 can be considered as a marker of diagnosis and prediction in cardiovascular events.

Genomic profiling of the transcription factor Zfp148 and its impact on the p53 pathway

Recent data suggest that the transcription factor Zfp148 represses activation of the tumor suppressor p53 in mice and that therapeutic targeting of the human orthologue ZNF148 could activate the p53 pathway without causing detrimental side effects. We have previously shown that Zfp148 deficiency promotes p53-dependent proliferation arrest of mouse embryonic fibroblasts (MEFs), but the underlying mechanism is not clear. Here, we showed that Zfp148 deficiency downregulated cell cycle genes in MEFs in a p53-dependent manner. Proliferation arrest of Zfp148-deficient cells required increased expression of ARF, a potent activator of the p53 pathway. Chromatin immunoprecipitation showed that Zfp148 bound to the ARF promoter, suggesting that Zfp148 represses ARF transcription. However, Zfp148 preferentially bound to promoters of other transcription factors, indicating that deletion of Zfp148 may have pleiotropic effects that activate ARF and p53 indirectly. In line with this, we found no evidence of genetic interaction between TP53 and ZNF148 in CRISPR and siRNA screen data from hundreds of human cancer cell lines. We conclude that Zfp148 deficiency, by increasing ARF transcription, downregulates cell cycle genes and cell proliferation in a p53-dependent manner. However, the lack of genetic interaction between ZNF148 and TP53 in human cancer cells suggests that therapeutic targeting of ZNF148 may not increase p53 activity in humans.

Matrix Metalloproteinase 3 Gene Polymorphism and Its Level Predict Morbidity After Acute Myocardial Infarction

OBJECTIVES

Matrix metalloproteinase is responsible for ventricular remodeling after acute myocardial infarction (MI). The purpose of the present study was to determine whether the matrix metalloproteinase 3 (MMP-3) polymorphism and its level predict morbidity after acute MI (AMI).

METHODS

We studied 112 patients with AMI and 140 controls. All patients were followed for AMI complications during their hospitalization and 6 months after. Serum MMP-3 was measured. MMP-3-1612 5A/6A polymorphism was genotyped by polymerase chain reaction.

RESULTS

We observed that the serum MMP-3 levels were significantly increased in patients with AMI with morbidity compared with patients without complications. Also, MMP-3 levels in patients with AMI carrying 5A/5A were elevated compared with those carrying 6A/6A. The frequencies of 5A/5A genotypes were significantly increased in patients with AMI compared with controls, and patients with AMI carrying 5A/5A had a fivefold increased risk of developing morbidity. The impairment of left ventricular function (ΔFS [fractional shortening] and ΔEF [ejection fraction]) was observed more in the 5A/5A genotype compared with the 6A/6A genotype. A significant inverse correlation between predischarge MMP-3 levels and FS and EF was found at 6 months follow-up.

CONCLUSIONS

MMP-3 polymorphism has a significant association with the risk of developing morbidity after AMI. Higher predischarge MMP-3 levels are associated with left ventricular dysfunction after AMI.

Genetic variation in the matrix metalloproteinase genes and diabetic nephropathy in type 1 diabetes

Genetic data support the notion that polymorphisms in members of the matrix metalloproteinase (MMP) family of genes play an important role in extracellular matrix remodeling and contribute to the pathogenesis of vascular disease. To identify novel genetic markers for diabetic nephropathy (DN), we examined the relationship between MMP gene polymorphisms and DN in the Genetics of Kidneys in Diabetes (GoKinD) population. Genotypic data from the Genetic Association Information Network (GAIN) type 1 DN project were analyzed for associations across 21 MMP genes in 1705 individual with type 1 diabetes, including 885 normoalbuminuric control subjects and 820 advanced DN case subjects. In total, we investigated the role of 1283 SNPs (198 genotyped SNPs and 1085 imputed SNPs) mapping to the MMP genes. We identified associations at several correlated SNPs across a 29.2kb interval on chromosome 11q at the MMP-3/MMP-12 locus. The strongest associations occurred at 2 highly-correlated SNPs, rs610950 (OR=0.50, P=1.6×10(-5)) and rs1277718 (OR=0.50, P=2.1×10(-5)). Further examination of this locus identified 17 SNPs (2 genotyped SNPs and 15 imputed SNPs) in complete linkage disequilibrium associated with DN (P-values<2.5×10(-4)), including a non-synonymous SNP (rs652438, Asn357Ser) located in exon 8 of MMP-12 that significantly reduced the risk of DN among carriers of the serine substitution relative to homozygous carriers of asparagine (OR=0.51; 95% CI=0.37-0.71, P=6.2×10(-5)). Taken together, our study suggests that genetic variations within the MMP-3/MMP-12 locus influence susceptibility of DN in type 1 diabetes.

NF-kappaB and ZBP-89 regulate MMP-3 expression via a polymorphic site in the promoter

A 5T/6T polymorphism in the human MMP-3 promoter affects gene expression and impacts the risk and/or severity of various pathological conditions. Chromatin immunoprecipitation (ChIP) in human fibroblasts homozygous for the 6T site demonstrate that it is bound by NF-kappaB and ZBP-89 transcription factors in its native chromatin. ChIP in COS-1 cells transfected with plasmids containing the 5T and 6T sites in the context of 2kb of the MMP-3 promoter showed that NF-kappaB p50 binds preferentially to the 6T site, while more ZBP-89 binding is detected to the 5T site. Over-expressed ZBP-89 increased transcription from the 5T promoter but not from the 6T, while NF-kappaB decreased transcription from both promoters, even in the presence of excess ZBP-89. A model is suggested in which the physiological impact of the polymorphism is dependent on the relative levels and activities of these competing factors in various cell types and conditions.

The transcriptional repressor ZBP-89 and the lack of Sp1/Sp3, c-Jun and Stat3 are important for the down-regulation of the vimentin gene during C2C12 myogenesis

Currently, considerable information is available about how muscle-specific genes are activated during myogenesis, yet little is known about how non-muscle genes are down-regulated. The intermediate filament protein vimentin is known to be "turned off" during myogenesis to be replaced by desmin, the muscle-specific intermediate filament protein. Here, we demonstrate that vimentin down-regulation is the result of the combined effect of several transcription factors. Levels of the positive activators, Sp1/Sp3, which are essential for vimentin expression, decrease during myogenesis. In addition, c-Jun and Stat3, two additional positive-acting transcription factors for vimentin gene expression, are also down-regulated. Over-expression via adenoviral approaches demonstrates that the up-regulation of the repressor ZBP-89 is critical to vimentin down-regulation. Elimination of ZBP-89 via siRNA blocks the down-regulation of vimentin and Sp1/Sp3 expression. From these studies we conclude that the combinatorial effect of the down-regulation of positive-acting transcription factors such as Sp1/Sp3, c-Jun and Stat3 versus the up-regulation of the repressor ZBP-89 contributes to the "turning off" of the vimentin gene during myogenesis.

Over-expression of the transcription factor, ZBP-89, leads to enhancement of the C2C12 myogenic program

Myogenesis involves the complex interplay between the down-regulation of non-muscle genes and the up-regulation of muscle-specific genes. This interplay is controlled by the myogenic regulatory factors Myf5, MRF4, MyoD and myogenin. To trigger the up-regulation of these muscle-specific factors, certain environmental cues, such as the removal of serum, signal C2C12 myoblast cells to withdraw from cell cycle, fuse and activate muscle-specific genes. Here, the level of ZBP-89 (zfp148), a Krüppel-like transcription factor, has been shown to increase during myogenesis. Over-expression of ZBP-89, via adenoviral infection, led to the enhancement of the myogenic program without requiring the removal of serum. Quantitative real-time PCR and ChIP assays documented that ZBP-89 promoted the down-regulation of Pax7 coupled with the up-regulation of MRF4 and MyoD to regulate C2C12 differentiation in vitro. In addition, ZBP-89 over-expression up-regulated p21 and Rb while promoting the down-regulation of cyclinA and cyclinD1. In converse, the diminution of ZBP-89 by siRNA promoted the retention of myogenic and cell cycle regulators at myoblast levels resulting in a concomitant delay of the myogenic program. From these studies we conclude that the transcription factor ZBP-89 plays an important role in the timing of the myogenic program.

Genetic polymorphisms of matrix metalloproteinase 12 and 13 genes are implicated in endometriosis progression

BACKGROUND

Matrix metalloproteinases (MMPs) may contribute to endometriosis. We tested whether eight functional polymorphisms of these genes could modify the risk of endometriosis.

METHODS

In this case-control study, 227 endometriosis and 241 controls were genotyped for MMP1 -1607 1G/2G, MMP2 -1575 G/A (MMP2.1), -1306 C/T (MMP2.2), MMP3 -1612 5A/6A, MMP7 -153 C/T (MMP7.1), -181 A/G (MMP7.2), MMP12 -82 A/G and MMP13-77 A/G. Association between MMP genotypes and superficial (SUP), deep infiltrating (DIE) and endometriomas (OMA) was tested for each polymorphism separately, using unconditional logistic regression and then for combined genotypes, using the combination test.

RESULTS

When considering all cases, MMP2 polymorphisms were found to be significant, mainly due to DIE (P = 0.023). A small difference between SUP and controls was found for MMP7.2 (P = 0.032) and MMP12 (P = 0.035), in the absence of correction for multiple testing. Using the combination test, the best association when comparing SUP with controls was obtained for MMP12-MMP13 (P = 0.004) for the combined genotype A/G-A/A (odds ratio = 27.60, 95% confidence interval: 2.80-272.40).

CONCLUSIONS

These data show a potential role for MMP12 -82 A/G and MMP13 -77 A/G combined polymorphisms in superficial endometriosis. As no association was found with deep infiltrating endometriosis, this combination of polymorphisms might protect from a more in-depth penetration of tissues.

Sumoylation-dependent control of homotypic and heterotypic synergy by the Kruppel-type zinc finger protein ZBP-89

The Krüppel-like transcription factor ZBP-89 is a sequence-specific regulator that plays key roles in cellular growth and differentiation especially in endodermal and germ cell lineages. ZBP-89 shares with other members of the Sp-like family an overlapping sequence specificity for GC-rich sequences in the regulatory regions of multiple genes. Defining the mechanisms that govern the intrinsic function of ZBP-89 as well as its competitive and non-competitive functional interactions with other regulators is central to understand how ZBP-89 exerts its biological functions. We now describe that post-translational modification of ZBP-89 by multiple small ubiquitin-like modifier (SUMO) isoforms occurs at two conserved synergy control motifs flanking the DNA binding domain. Functionally sumoylation did not directly alter the ability of ZBP-89 to compete with other Sp-like factors from individual sites. At promoters bearing multiple response elements, however, this modification inhibited the functional cooperation between ZBP-89 and Sp1. Analysis of the properties of ZBP-89 in cellular contexts devoid of competing factors indicated that although on its own it behaves as a modest activator it potently synergizes with heterologous activators such as the glucocorticoid receptor. Notably we found that when conjugated to ZBP-89, SUMO exerts a strong inhibitory effect on such synergistic interactions through a critical conserved functional surface. By regulating higher order functional interactions, sumoylation provides a reversible post-translational mechanism to control the activity of ZBP-89.

The zinc finger repressor, ZBP-89, recruits histone deacetylase 1 to repress vimentin gene expression

Vimentin, a member of the intermediate filament (IF) protein family, exhibits a complex pattern of tissue- and developmental-specific expression. Although vimentin is widely expressed in the embryo, its expression becomes restricted during terminal differentiation. Moreover, it is often expressed in tissue culture cells despite their embryological origin and is a marker for the metastatic tumor cell. Previously, the vimentin promoter has been shown to contain several positive- and negative-acting cis-elements. The negative elements bind the transcription factor ZBP-89. Interestingly, ZBP-89 can be either an activator or a repressor of gene expression. For instance, ZBP-89 has been shown to activate p21(waf1/cip1) expression by recruiting p300 to the p21 promoter. Here, we have investigated the mechanism of ZBP-89 repression. The histone deacetylase (HDAC) inhibitor TSA enhances vimentin gene expression requiring the proximal promoter region including GC-box 1, a known Sp1/Sp3 binding site. Chromatin immunoprecipitation (ChIP) assays document an increase in the acetylation status of histone H3 on the endogenous vimentin gene concomitant with TSA treatment. However, EMSAs, DNA precipitation, co-immunoprecipitation and ChIP data show that it is not Sp1, but rather ZBP-89, which recruits HDAC1. From these studies we conclude that ZBP-89 functions as a repressor by recruiting HDAC1 to the vimentin promoter.

Regulation of matrix metalloproteinase gene expression

The metalloproteinases degrade extracellular matrix (ECM) components and activate growth factors, thereby contributing to physiological events (tissue remodeling in pregnancy, wound healing, angiogenesis) and pathological conditions (cancer, arthritis, periodontitis). The intent of this review is to bring together various studies on transcriptional and post-transcriptional control of metalloproteinase expression. Certainly, much information is known as to the cis-elements and corresponding trans-activators regulating expression of these genes. We discuss the fact that a number of the metalloproteinase promoters share common structural features and, therefore, not surprisingly are co-regulated in their expression to some extent. More recently, much effort has been devoted to understanding the role of chromatin in regulating gene expression. While this area has been understudied with respect to matrix metalloproteinase (MMP) regulation, the literature indicates a convincing role for both histone modifications and chromatin-remodeling motors in controlling expression of multiple metalloproteinases. In addition to transcriptional control, mRNA stability and protein translation also contribute to the metalloproteinase product amount. We discuss such studies and how various biological cues, including TGF-beta, regulate the levels of certain collagenases either solely through mRNA stabilization or by jointly targeting transcriptional and post-transcriptional mechanisms. We also discuss the current deficits in our knowledge, concerning tissue-specific expression and why despite elevated amounts/activity of trans-activators targeting MMP promoters in tumor cells, nevertheless, MMP expression is largely restricted to the stromal compartment. Finally, we argue for potential technologies to regulate MMP expression of utility in pathological conditions where these enzymes are aberrantly expressed.

Differential expression of matrix metalloproteinase 3 (MMP3) in preadipocytes/stromal vascular cells from nonobese nondiabetic versus obese nondiabetic Pima Indians

Prior microarray studies comparing global gene expression patterns in preadipocytes/stromal vascular cells isolated from nonobese nondiabetic versus obese nondiabetic Pima Indians showed that matrix metalloproteinase 9 (MMP9) is upregulated in obese subjects. The current study targeted analysis of nine additional MMP genes that cluster to a region on chromosome 11q22 that is linked to BMI and percent body fat. Differential-display PCR showed that MMP3 is downregulated in preadipocytes/stromal vascular cells from obese subjects, and real-time PCR showed that MMP3 expression levels are negatively correlated with percent body fat. To determine whether variants within MMP3 are responsible for its altered expression, MMP3 was sequenced, and seven representative variants were genotyped in 1,037 Pima subjects for association analyses. Two variants were associated with both BMI and type 2 diabetes, and two additional variants were associated with type 2 diabetes alone; however, none of these variants were associated with MMP3 expression levels. We propose that the MMP3 pathway is altered in human obesity, but this alteration may be the result of a combination of genetic variation within the MMP3 locus itself, as well as variation in additional factors, either primary or secondary to obesity, that regulate expression of the MMP3 gene.

Allele-specific MMP-3 transcription under in vivo conditions

A common matrix metalloproteinases-3 (MMP-3) -1612 5A/6A promoter polymorphism is associated with risk for cardiovascular disease, rheumatoid arthritis, and other diseases. Here we used the haplotype chromatin immunoprecipitation method to study allele-specific MMP-3 expression under in vivo conditions in heterozygous THP-1 cells. Pyrosequencing was used to analyse the ratio of 5A-allele to 6A-allele after chromatin immunoprecipitation using an antibody against phosphorylated active RNA polymerase II. There was no allele-specific difference in transcriptional activity during basal conditions, i.e., in unstimulated monocytic THP-1 cells. However, after stimulation of MMP-3 expression by monocyte differentiation or incubation with IL-1beta, the haplotype containing the 5A-allele was associated with higher transcriptional activity compared with the 6A-containing haplotype. Electromobility shift assay demonstrated increased binding of nuclear proteins to the 5A-allele after monocyte differentiation. In conclusion, the common MMP-3 5A/6A promoter polymorphism appears to be functional only during specific environmental conditions involving inflammation.

Identification of zinc finger binding protein 89 (ZBP-89) as a transcriptional activator for a major bovine growth hormone receptor promoter

The objective of this study was to identify the transcription factors that regulate the expression of growth hormone receptor (GHR) 1A mRNA, a major GHR mRNA variant in the bovine liver. A deoxyribonuclease I footprint analysis revealed that the GHR1A promoter region -69 to -30 (relative to the transcription start site for GHR1A mRNA) contained binding sites for bovine liver nuclear proteins. Using a yeast one-hybrid analysis, zinc finger binding protein 89 (ZBP-89) was identified as a binding protein to this promoter region. Binding of ZBP-89 to the GHR1A promoter region -69 to -30 was further confirmed by an electrophoretic mobility shift assay. In cotransfection analyses, overexpression of ZBP-89 enhanced (P<0.01) the activity of the GHR1A promoter and this enhancement was dependent on the putative ZBP-89 binding site in the promoter. These results together indicate that ZBP-89 is a transcription factor that regulates the expression of GHR1A mRNA.

Stromelysin-1 expression is activated in vivo by Ets-1 through palindromic head-to-head Ets binding sites present in the promoter

Regulation of the gene expression of Stromelysin-1 (matrix metalloproteinase-3), a member of the matrix metalloproteinase family, is critical for tissue homeostasis. The Stromelysin-1 promoter is known to be transactivated by Ets proteins through palindromic head-to-head Ets binding sites (EBS), an unusual configuration among metalloproteinase promoters. Patterns of increased co-expression of Stromelysin-1 and Ets-1 genes have been observed in pathological processes such as rheumatoid arthritis, glomerulonephritis and tumor invasion. In this context, we show in a synovial fibroblastic model cell line (HIG-82), which is able to co-express Stromelysin-1 and Ets-1, that the EBS palindrome is essential for the expression of Stromelysin-1. More precisely, using electrophoretic mobility shift assays, DNA affinity purification and chromatin immunoprecipitation, we demonstrate that endogenous Ets-1, but not Ets-2, is present on this palindrome. The use of a dominant-negative form of Ets-1 and the decrease of Ets-1 amount either by fumagillin, an antiangiogenic compound, or by short interfering RNA show that the activation rate of the promoter and the expression of Stromelysin-1 correlate with the level of endogenous Ets-1. Thus, it is the first demonstration, using this cellular model, that endogenously expressed Ets-1 is actually a main activator of the Stromelysin-1 promoter through its effective binding to the EBS palindrome.

Intestinal alkaline phosphatase gene expression is activated by ZBP-89

Intestinal alkaline phosphatase (IAP) is an enterocyte differentiation marker that functions to limit fat absorption. Zinc finger binding protein-89 (ZBP-89) is a Kruppel-type transcription factor that appears to promote a differentiated phenotype in the intestinal epithelium. The purpose of this study was to investigate the regulation of IAP gene expression by ZBP-89. RT-PCR, quantitative real-time RT-PCR, Western blot analyses, and reporter assays were used to determine the regulation of IAP by ZBP-89 in HT-29 and Caco-2 colon cancer cells. ZBP-89 knockdown was achieved by specific short interfering (si)RNA. EMSA and chromatin immunoprecipitation (ChIP) were performed to examine the binding of ZBP-89 to the IAP promoter. The results of RT-PCR, quantitative real-time PCR, and Western blot analyses showed that ZBP-89 was expressed at low levels in Caco-2 and HT-29 cells, whereas IAP was minimally expressed and absent in these cells, respectively. Transfection with ZBP-89 expression plamid increased IAP mRNA and protein levels in both cell lines, whereas knockdown of endogenous ZBP-89 by siRNA reduced basal levels of IAP gene expression in Caco-2 cells. IAP-luciferase reporter assays, EMSA, and ChIP established that ZBP-89 activated the IAP gene through a response element (ZBP-89 response element: 5'-CCTCCTCCC-3') located between -1018 and -1010 bp upstream of the AUG start codon. We conclude that ZBP-89 is a direct transcriptional activator of the enterocyte differentiation marker IAP. These findings are consistent with the role that this transcription factor is thought to play as a tumor suppressor and suggests its possible function in the physiology of fat absorption.

A PDGFRA promoter polymorphism, which disrupts the binding of ZNF148, is associated with primitive neuroectodermal tumours and ependymomas

BACKGROUND

Platelet derived growth factor receptor alpha (PDGFRalpha) expression is typical for a variety of brain tumours, while in normal adult brain PDGFRalpha expression is limited to a small number of neural progenitor cells. The molecular mechanisms responsible for the PDGFRalpha expression in tumours are not known, but in the absence of amplification, changes in transcriptional regulation might be an important factor in this process.

METHODS AND RESULTS

We have investigated the link between single nucleotide polymorphisms (SNPs) within the PDGFRalpha gene promoter and the occurrence of brain tumours (medulloblastomas, supratentorial primitive neuroectodermal tumours (PNETs), ependymal tumours, astrocytomas, oligodendrogliomas, and mixed gliomas). These SNPs give rise to five different promoter haplotypes named H1 and H2alpha-delta. It is apparent from the haplotype frequency distribution that both PNET (10-fold) and ependymoma (6.5-fold) patient groups display a significant over-representation of the H2delta haplotype. The precise functional role in PDGFRalpha gene transcription for the H2delta haplotype is not known yet, but we can show that the H2delta haplotype specifically disrupts binding of the transcription factor ZNF148 as compared to the other promoter haplotypes.

CONCLUSIONS

The specific over-representation of the H2delta haplotype in both patients with PNETs and ependymomas suggests a functional role for the ZNF148/PDGFRalpha pathway in the pathogenesis of these tumours.

Impairment of stromelysin-1 transcriptional activity by promoter mutations in high microsatellite instability colorectal tumors

Colorectal tumorigenesis is characterized by the sequential inactivation of a series of tumor suppressor genes (microsatellite-stable tumors) and genetic or epigenetic alterations in mismatch repair genes in nonpoliposic hereditary tumours and 13% to 15% of sporadic colorectal cancer [high microsatellite instability (MSI-H) tumors]. We hypothesized a molecular mechanism for MSI-H colorectal tumors related to matrix metalloproteinase 3 (MMP-3) promoter mutations, down-regulation of MMP-3 expression, and impairment of MMP-9 activation. We have now analyzed the 2.2-kb full MMP-3 promoter to assess the mutation distribution. The mutations found are restricted to the polymorphic region that includes the zinc-binding protein (ZBP-89) binding element. To show that these alterations were the cause of the low expression of this gene, we have generated three constructs with different MMP-3 promoters (wild type and two mutants) and we have expressed them in SW480 human colorectal cells. The basal transcriptional activity of wild-type MMP-3 promoter was much higher than the mutants activity. In addition, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced transcriptional activity of wild-type MMP-3 promoter was 10-fold higher than the mutants activity. Dexamethasone inhibited the basal transcriptional activity of wild-type MMP-3 promoter and of the two mutants found in the MSI-H subgroup of colorectal tumors. Significantly, dexamethasone almost completely blunted the TPA-induced effect on wild-type MMP-3 promoter transcriptional activity and on the mutants, even below their basal activity. Our data show that mutations found in the polymorphic region of the MMP-3 promoter from MSI-H colorectal tumors impair its basal and induced transcriptional activity, which may contribute to their better clinical outcome.

The Epstein-Barr virus protein BMRF1 activates gastrin transcription

The Epstein-Barr virus (EBV) BMRF1 gene encodes an early lytic protein that functions not only as the viral DNA polymerase processivity factor but also as a transcriptional activator. BMRF1 has been previously shown to activate transcription of an EBV early promoter, BHLF1, though a GC-rich motif which binds to SP1 and ZBP-89, although the exact mechanism for this effect is not known (D. J. Law, S. A. Tarle, and J. L. Merchant, Mamm. Genome 9:165-167, 1998). Here we demonstrate that BMRF1 activates transcription of the cellular gastrin gene in telomerase-immortalized keratinocytes. Furthermore, BMRF1 activated a reporter gene construct driven by the gastrin promoter in a variety of cell types, and this effect was mediated by two SP1/ZBP-89 binding sites in the gastrin promoter. ZBP-89 has been previously shown to negatively regulate the gastrin promoter. However, ZBP-89 can function as either a negative or positive regulator of transcription, depending upon the promoter and perhaps other, as-yet-unidentified factors. BMRF1 increased the binding of ZBP-89 to the gastrin promoter, and a ZBP-89-GAL4 fusion protein was converted into a positive transcriptional regulator by cotransfection with BMRF1. BMRF1 also enhanced the transcriptional activity of an SP1-GAL4 fusion protein. These results suggest that BMRF1 activates target promoters through its effect on both the SP1 and ZBP-89 transcription factors. Furthermore, as the EBV genome is present in up to 10% of gastric cancers, and the different forms of gastrin are growth factors for gastrointestinal epithelium, our results suggest a mechanism by which lytic EBV infection could promote the growth of gastric cells.

Positive selection on MMP3 regulation has shaped heart disease risk

BACKGROUND

The evolutionary forces of mutation, natural selection, and genetic drift shape the pattern of phenotypic variation in nature, but the roles of these forces in defining the distributions of particular traits have been hard to disentangle. To better understand the mechanisms contributing to common variation in humans, we investigated the evolutionary history of a functional polymorphism in the upstream regulatory region of the MMP3 gene. This single base pair insertion/deletion variant, which results in a run of either 5 or 6 thymidines 1608 bp from the transcription start site, alters transcription factor binding and influences levels of MMP3 mRNA and protein. The polymorphism contributes to variation in arterial traits and to the risk of coronary heart disease and its progression.

RESULTS

Phylogenetic and population genetic analysis of primate sequences indicate that the binding site region is rapidly evolving and has been a hot spot for mutation for tens of millions of years. We also find evidence for the action of positive selection, beginning approximately 24,000 years ago, increasing the frequency of the high-expression allele in Europe but not elsewhere. Positive selection is evident in statistical tests of differentiation among populations and haplotype diversity within populations. Europeans have greater arterial elasticity and suffer dramatically fewer coronary heart disease events than they would have had this selection not occurred.

CONCLUSIONS

Locally elevated mutation rates and strong positive selection on a cis-regulatory variant have shaped contemporary phenotypic variation and public health.

Association of matrix metalloproteinase 3 promoter genotype with disease outcome in rheumatoid arthritis

Matrix metalloproteinases (MMPs) are implicated in joint destruction in rheumatoid arthritis (RA). We investigated whether the 5A/6A polymorphism within the MMP-3 (stromelysin-1) gene promoter region is associated with disease outcome in 254 patients with established RA. Patients homozygous for the MMP-3 6A allele had more radiographic damage (measured by Larsen score) than those with other genotypes (109.8 vs 91.1, P=0.04). Patients with the 6A/6A genotype also had more functional impairment and higher serum proMMP-3 levels, although only the latter was significant (P=0.002). A possible association was found between homozygosity for the 6A allele and carriage of the RA-associated HLA-DRB1 shared epitope (SE). Combination of these factors was associated with more severe disease than the SE alone. The data suggest that the MMP-3 6A/6A genotype is associated with worse RA outcome, and that this genotype may have an additive effect with the SE on disease severity.

NF-kappaB binds to a polymorphic repressor element in the MMP-3 promoter

A 5T/6T polymorphic site in the matrix metalloproteinase-3 (MMP-3) promoter has been identified as a repressor element involved in inhibiting induction of MMP-3 transcription by interleukin 1; and the 6T allele has been associated with decreased expression of MMP-3 as compared to the 5T allele. Zinc-binding protein-89 (ZBP-89) was cloned from a yeast one-hybrid assay via its ability to interact with this site, but when the protein was over-expressed, it resulted in activation of the MMP-3 promoter rather than repression. Here we show that in nuclear extracts isolated from human gingival fibroblasts stimulated with IL-1, this site is bound by p50 and p65 components of NF-kappaB in addition to ZBP-89, and that recombinant p50 binds preferentially to the 6T binding site. These results are consistent with a role for NF-kappaB in limiting the cytokine induced expression of MMP-3.

Stat3 enhances vimentin gene expression by binding to the antisilencer element and interacting with the repressor protein, ZBP-89

Vimentin exhibits a complex pattern of developmental- and tissue-specific expression and is aberrantly expressed in most metastatic tumors. The human vimentin promoter contains multiple DNA elements, some of which enhance gene expression and one that inhibits. A silencer element (at -319) binds the repressor ZBP-89. Further upstream (at -757) is an element, which acts positively in the presence of the silencer element and, thus, is referred to as an antisilencer (ASE). Previously, we showed that Stat1alpha binds to this element upon induction by IFN-gamma. However, substantial binding and reporter gene activity was still present in nontreated cells. Here, we have found that Stat3 binds to the ASE element in vitro. Transfection experiments in COS-1 cells with various vimentin promoter--reporter constructs show that gene activity is dependent upon the cotransfection and activation of Stat3. Moreover, activated Stat3 can overcome ZBP-89 repression. Coimmunoprecipitation studies demonstrate that Stat3 and ZBP-89 can interact and confocal microscopy detects these factors to be colocalized in the nucleus. Moreover, a correlation exists between the presence of activated Stat3 and vimentin expression in MDA-MB-231 cells, which is lacking in MCF7 cells where vimentin is not expressed. In the light of these results, we propose that the interaction of Stat3 and ZBP-89 may be crucial for overcoming the effects of the repressor ZBP-89, which suggests a novel mode for Stat3 gene activation.

ZBP-89 mediates butyrate regulation of gene expression

Inducible p53-independent regulation of the cyclin-dependent kinase inhibitor p21(Waf1) transcription is mediated through its proximal GC-rich sites. Prior studies have shown that Sp1, Sp3 and the histone acetyltransferase coactivator p300 are components of the complexes that bind to these sites. Although Sp1 and Sp3 collaborate with p300, a direct interaction between Sp1 and p300 does not occur. Zinc-finger binding protein-89 (ZBP-89, also known as BFCOL1, BERF-1 and ZNF-148) is a Krüppel-type zinc-finger transcription factor that binds to the same GC-rich sequences as Sp1. We sought to determine whether ZBP-89 is a target of p300 during butyrate induction of p21(Waf1). This review summarizes the evidence that supports a crucial role for ZBP-89 in butyrate regulation of p21(Waf1). Adenovirus-mediated expression of ZBP-89 in HT-29 cells reveals that ZBP-89 potentiates butyrate induction of endogenous p21(Waf1) gene expression. DNA-protein interaction assays demonstrate that Sp1, Sp3 and ZBP-89 bind the p21(Waf1) promoter at -245 to -215. Coprecipitation assays reveal that p300 preferentially binds to the N-terminus of ZBP-89. ZBP-89 also induces p21(Waf1) through stabilization of p53. Although ZBP-89 binds mutant and wild-type p53, only wild-type p53 is stabilized. Moreover, mutant p53 shifts the subnuclear location of ZBP-89 to the nuclear periphery, which is a domain rich in heterochromatin. This finding led to the conclusion that mutant p53 exerts a dominant negative effect on ZBP-89. We propose that gene silencing by mutant p53 might be mediated by sequestering ZBP-89 within heterochromatin regions at the nuclear periphery. Overall, ZBP-89 is a butyrate-regulated coactivator of p53 and is able to induce p21(Waf1) gene expression through both p53-dependent and -independent mechanisms to inhibit cell growth.

Influences of matrix metalloproteinase-3 gene variation on extent of coronary atherosclerosis and risk of myocardial infarction

OBJECTIVES

The aim of this study was to assess matrix metalloproteinase-3 (MMP3) gene variation in relation to the degree of coronary atherosclerosis and risk of myocardial infarction (MI) in patients with coronary artery disease.

METHODS

In this study, we systematically screened the promoter and coding regions for sequence variants. All polymorphisms identified were analyzed in 1,240 individuals undergoing coronary angiography. Functional analyses of the polymorphisms were carried out with the use of report assays and electrophoretic mobility shift assays.

RESULTS

Six novel polymorphisms were identified. The 6A/6A genotype was associated with greater number of coronary arteries with significant stenosis (odds ratio [OR] 1.52, p = 0.008), whereas the 5A/5A and 5A/6A genotypes were associated with increased risk of MI (OR 2.02 and 1.78, p = 0.016 and 0.032, respectively). A stepwise logistic regression analysis with all polymorphisms taken into account showed that the effect of MI susceptibility was largely attributed to the 5A/6A polymorphism. In a stepwise logistic regression analysis with all haplotypes as independent variables, the most common haplotype (T-5A-A-A-G-A), and two rare haplotypes, all containing the 5A allele, were associated with MI susceptibility. Functional studies showed that the T-5A-A-A-G-A haplotype had a higher promoter activity in macrophages.

CONCLUSIONS

These data indicate that the effect of MMP3 gene variation is attributable to the 5A/6A polymorphism and that individuals carrying the 6A/6A genotype may be predisposed to developing atherosclerotic plaques with significant stenosis, whereas those carrying the 5A allele may be predisposed to developing unstable plaques.

ZBP-89 represses vimentin gene transcription by interacting with the transcriptional activator, Sp1

Vimentin, a member of the intermediate filament protein family, is regulated both developmentally and tissue specifically. It is also a marker of the metastatic potential of many tumor cells. Pre viously, the human vimentin promoter has been shown to contain multiple elements for the binding of both positive- and negative-acting regulatory factors. Transient transfection analysis of various vimentin 5'-end promoter sequences and mutants thereof fused to a reporter gene further defined two regulatory elements, a positive element that binds Sp1 and a negative element that binds the protein ZBP-89. ZBP-89 has been shown to be either a repressor or an activator of gene expression, depending on the promoter. Here, we show that for vimentin, both ZBP-89 and ZBP-99 repress reporter gene expression in Schneider (S2) cells. Deletion constructs confirm that the glutamine-rich region of Sp1 is required to enhance vimentin transcription, whereas the N-terminus of ZBP-89 is required to interact with Sp1 and repress gene expression. The overexpression of hTAF(II)130 can alleviate ZBP-89 repression in S2 cells, suggesting how ZBP-89 might serve to block gene expression.

The zinc finger transcription factor ZBP-89 is a repressor of the human beta 2-integrin CD11b gene

Integrin CD11b is a differentiation marker of the myelomonocytic lineage and an important mediator of inflammation. Expression of the CD11b gene is transcriptionally induced as myeloid precursors differentiate into mature cells, then drops as monocytes further differentiate into macrophages. Previous studies have identified elements and factors involved in the transcriptional activation of the CD11b gene during myeloid differentiation, but no data exist regarding potential down-regulatory factors, especially in the later stages of differentiation. Using 2 copies of a GC-rich element (-141 to -110) in the CD11b promoter, we probed a cDNA expression library for interacting proteins. Three clones were identified among 9.1 million screened, all encoding the DNA-binding domain of the zinc finger factor ZBP-89. Overexpression of ZBP-89 in the monocyte precursor cell line U937 reduced CD11b promoter-driven luciferase activity when U937 cells were induced to differentiate into monocytelike cells using phorbol esters. To identify the differentiation stage at which ZBP-89 repression of the CD11b gene is exerted, the protein level of ZBP-89 was correlated with that of CD11b mRNA in differentiating U937 as well as in normal human monocytes undergoing in vitro differentiation into macrophages. A clear inverse relationship was observed in the latter but not the former state, suggesting that ZBP-89 represses CD11b gene expression during the further differentiation of monocytes into macrophages.

ETS-1 transcription factor binds cooperatively to the palindromic head to head ETS-binding sites of the stromelysin-1 promoter by counteracting autoinhibition

Stromelysin-1 (matrix metalloproteinase-3) is a member of the matrix metalloproteinase family. Regulation of its gene expression is critical for tissue homeostasis. Patterns of increased co-expression of stromelysin-1 and ETS-1 genes have been observed in pathological processes. Stromelysin-1 promoter is transactivated by ETS proteins through two palindromic head to head ETS-binding sites, an unusual configuration among metalloproteinase promoters. By using surface plasmon resonance, electrophoretic mobility shift assay, and photo-cross-linking, we showed that full-length human ETS-1 (p51) binds cooperatively to the ETS-binding site palindrome of the human stromelysin-1 promoter, with facilitated binding of the second ETS-1 molecule to form an ETS-1.DNA.ETS-1 ternary complex. The study of N-terminal deletion mutants allowed us to conclude that cooperative binding implied autoinhibition counteraction, requiring the 245-330-residue region of the protein that is encoded by exon VII of the gene. This region was deleted in the natural p42 isoform of ETS-1, which was unable to bind cooperatively to the palindrome. Transient transfection experiments showed a good correlation between DNA binding and promoter transactivation for p51. In contrast, p42 showed a poorer transactivation, reinforcing the significance of cooperative binding for full transactivation. It is the first time that ETS-1 was shown to be able to counteract its own autoinhibition.

Identification and characterization of cell-specific enhancer elements for the mouse ETF/Tead2 gene

We have identified and characterized by transient transfection assays the cell-specific 117-bp enhancer sequence in the first intron of the mouse ETF (Embryonic TEA domain-containing factor)/Tead2 gene required for transcriptional activation in ETF/Tead2 gene-expressing cells, such as P19 cells. The 117-bp enhancer contains one GC-rich sequence (5'-GGGGCGGGG-3'), termed the GC box, and two tandemly repeated GA-rich sequences (5'-GGGGGAGGGG-3'), termed the proximal and distal GA elements. Further analyses, including transfection studies and electrophoretic mobility shift assays using a series of deletion and mutation constructs, indicated that Sp1, a putative activator, may be required to predominate over its competition with another unknown putative repressor, termed the GA element-binding factor, for binding to both the GC box, which overlapped with the proximal GA element, and the distal GA element in the 117-bp sequence in order to achieve a full enhancer activity. We also discuss a possible mechanism underlying the cell-specific enhancer activity of the 117-bp sequence.

ZBP-89, Sp1, and nuclear factor-kappa B regulate epithelial neutrophil-activating peptide-78 gene expression in Caco-2 human colonic epithelial cells

We reported previously that human colonic epithelial cells produce the C-X-C chemokine epithelial neutrophil-activating peptide-78 (ENA-78) and that its expression is up-regulated in ulcerative colitis. The aim of this study was to investigate the transcriptional regulation of ENA-78 gene expression in Caco-2 intestinal epithelial cells. Reporter gene transfection and electrophoretic mobility shift assay studies demonstrated that cooperation between two regions of the ENA-78 promoter were required for maximal gene expression in interleukin-1beta-stimulated Caco-2 cells. Binding of activated p50/p65 nuclear factor-kappaB to nucleotides -82 to -91 was essential for interleukin-1beta-dependent gene transcription, whereas binding of constitutively expressed zinc-requiring nuclear factors to nucleotides -125 to -134 (site A) was required for basal gene expression. Scanning mutagenesis of site A demonstrated overlapping binding elements at this locus. One site (CTCCCCC) bound Sp1 and Sp3, and overexpression of Sp1 (but not Sp3) up-regulated basal ENA-78 transcription. Another site (CCCCTCCCCC) was found to bind the zinc finger nuclear factor ZBP-89, and overexpression of this protein significantly repressed ENA-78 reporter gene activity. This study demonstrates that ENA-78 gene expression in Caco-2 intestinal epithelial cells is subject to complex regulation involving the coordinate binding of ZBP-89, Sp1, and nuclear factor-kappaB to the ENA-78 promoter.

Polymorphisms in matrix metalloproteinase-1, -3, -9, and -12 genes in relation to subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Intracranial aneurysm, which underlies the vast majority of subarachnoid hemorrhage incidences, has a multifactorial etiology, and the importance of genetic factors is increasingly recognized. Development and rupture of intracranial aneurysms involve degradation and remodeling of the vascular wall matrix in which the matrix metalloproteinases (MMPs) play an important role. The possible impact of MMP gene polymorphisms on susceptibility to intracranial aneurysms is still controversial, with conflicting data from different reported studies.

METHODS

In this study we analyzed 5 different functional promoter polymorphisms in the MMP-1, MMP-3, MMP-9, and MMP-12 genes in a sample of 92 patients with aneurysmal subarachnoid hemorrhage and 158 healthy control subjects, all from southern England.

RESULTS

No significant difference was detected between the patient and control groups in genotype distribution of any of the polymorphisms studied.

CONCLUSIONS

The data do not support the hypothesis that MMP gene variations influence the development of intracranial aneurysms in the population studied.

Identification and characterization of a transcriptional regulator for the lck proximal promoter

The lck gene encodes a protein-tyrosine kinase that plays a key role in signaling mediated through T cell receptor (TCR) and pre-TCR complexes. Transcription of the lck gene is regulated by two independent promoter elements: the proximal and distal promoters. Previous studies employing transgenic mice demonstrated that the sequence between -584 and -240 from the transcription start site in the mouse lck proximal promoter is required for its tissue-specific expression in the thymus. In this study, we demonstrate that a Krüppel-like zinc finger protein, mtbeta (BFCOL1, BERF-1, ZBP-89, ZNF148), previously cloned as a protein that binds to the CD3delta gene enhancer, binds to the -365 to -328 region of the lck proximal promoter. mtbeta is ubiquitously expressed in various cell lines and mouse tissues. Overexpressed mtbeta is more active in T-lineage cells than B-lineage cells for transactivating an artificial promoter consisting of the mtbeta binding site and a TATA box. Activity of the lck proximal promoter was significantly impaired by mutating the mtbeta binding site or by reducing mtbeta protein expression level by using antisense mRNA. Our results indicate that mtbeta activity is regulated in a tissue-specific manner and that mtbeta is a critical transactivator for the lck proximal promoter.

Conserved structure and promoter sequence similarity in the mouse and human genes encoding the zinc finger factor BERF-1/BFCOL1/ZBP-89

We have characterized the genomic structure of the mouse Zfp148 gene encoding Beta-Enolase Repressor Factor-1 (BERF-1), a Kruppel-like zinc finger protein involved in the transcriptional regulation of several genes, which is also termed ZBP-89, BFCOL1. The cloned Zfp148 gene spans 110 kb of genomic DNA encompassing the 5'-end region, 9 exons, 8 introns, and the 3'-untranslated region. The promoter region displays the typical features of a housekeeping gene: a high G+C content and the absence of canonical TATA and CAAT boxes consistent with the multiple transcription initiation sites determined by primary extension analysis. Computer-assisted search in the human genome database allowed us to determine that the same genomic structure with identical intron-exon organization is conserved in the human homologue ZNF 148. Functional analysis of the 5'-flanking sequence of the mouse gene indicated that the region from nucleotide -205 to +144, relative to the major transcription start site, contains cis-regulatory elements that promote basal expression. Such sequences and the overall promoter architecture are highly conserved in the human gene. Furthermore, we show that the complex transcription pattern of the Zfp148 gene might be due to a combination of alternative splicing and differential polyadenylation sites utilization.

Polymorphism in matrix metalloproteinase gene promoters: implication in regulation of gene expression and susceptibility of various diseases

The matrix metalloproteinases (MMPs) can degrade a range of extracellular matrix proteins and have been implicated in connective tissue destruction and remodelling associated with cancer invasion and metastasis, cartilage destruction in arthritis, atherosclerotic plaque rupture, and the development of aneurysms. Recently, naturally occurring sequence variation has been detected in the promoter of a number of MMP genes. These genetic polymorphisms have been shown to have allele-specific effects on the transcriptional activities of MMP gene promoters, and to be associated with susceptibility to coronary heart disease, aneurysms and cancers. These findings indicate that variation in the MMP genes may contribute to inter-individual differences in susceptibility to these common, complex diseases, likely through effects on the balance between the synthesis and degradation of extracellular matrix proteins.

Transcription factor ZBP-89 cooperates with histone acetyltransferase p300 during butyrate activation of p21waf1 transcription in human cells

Inducible p53-independent regulation of the cyclin-dependent kinase inhibitor p21(waf1) transcription is mediated through proximal GC-rich sites. Prior studies have shown that Sp1, Sp3, and the histone acetylase co-activator p300 are components of the complexes binding to these sites. Although Sp1 and Sp3 collaborate with p300, a direct interaction between Sp1 and p300 does not occur. This study sought to determine whether ZBP-89 rather than Sp1 is the direct target of p300 during butyrate induction of p21(waf1). ZBP-89 (BFCOL1, BERF-1, ZNF 148) is a Krüppel-type zinc finger transcription factor that binds to GC-rich elements and represses or activates known target genes. Adenoviral-mediated expression of ZBP-89 in HT-29 cells revealed that ZBP-89 potentiates butyrate induction of endogenous p21(waf1) gene expression. Further, cotransfection of a ZBP-89 expression vector with a 2.3-kilobase p21(waf1) reporter recapitulated the potentiation by butyrate. DNase I footprinting analysis of the human p21(waf1) promoter with recombinant ZBP-89 identified a binding site at -245 to -215. Electrophoretic mobility shift assays confirmed that both recombinant and endogenous ZBP-89 and Sp1 bind to this element. The potentiation was abolished in the presence of adenoviral protein E1A. Deletion of the N-terminal domain of ZBP-89 abolished the potentiation mediated by butyrate treatment. This same deletion mutant abolished the ZBP-89 interaction with p300. Cotransfection of p300 with ZBP-89 stimulated the p21(waf1) promoter in the absence of butyrate. p300 co-precipitated with ZBP-89 but not with Sp1, whereas ZBP-89 co-precipitated with Sp1. Together, these findings demonstrate that ZBP-89 also plays a critical role in butyrate activation of the p21(waf1) promoter and reveals preferential cooperation of this four-zinc finger transcription factor with p300.

Genetic diversity in the matrix metalloproteinase family. Effects on function and disease progression

Atherosclerosis is an example of a complex trait, where the course of the disease is influenced by a combination of common variation in a constellation of genes and the effect of a wide range of environmental variables. Thus, the underlying disease mechanisms will be modulated by genetic diversity and the effect this diversity has on an individual's response to environmental challenges such as smoking, diet, and exercise. Unlike the consequences of mutations in severe single-gene disorders on protein function, the impact of individual common, functionally important sequence changes in genes contributing to multifactorial diseases is likely to be very small. The challenge is to dissect the contribution that each of these genes makes to the disease process. We have tackled this by identifying common genetic variants, studying their effects on function, and applying them to the analysis of association in appropriately structured and suitably powered studies. Even with our incomplete understanding of the disease, the list of potential candidate genes we could study is vast; but, we do know from pathological studies that a wide spectrum of structural architecture exists in atherosclerotic plaques, suggesting that remodeling of vascular connective tissue is fundamentally important. Matrix remodeling is controlled by a complex network of cell and matrix interactions, the net outcome of which is the product of a balance between synthetic and degradative processes. Our work has focused on the family of enzymes and inhibitors most directly associated with matrix turnover--the matrix metalloproteinases (MMPs) and their natural inhibitors (TIMPs, tissue inhibitors of MPs). We specifically searched for functionally relevant genetic variants that might modulate the delicate control of matrix turnover. Using these molecular genetic strategies to investigate the impact of natural genetic variation on vascular matrix remodeling has begun to shed new light on the importance of these genes in atherogenesis.

ZBP-99 defines a conserved family of transcription factors and regulates ornithine decarboxylase gene expression

Among transcription factors that regulate ornithine decarboxylase (ODC) gene expression are those that interact with GC-rich promoters, including Sp1 and ZBP-89. Sp1 functions as a transactivator and ZBP-89 as a transrepressor of both the ODC and gastrin promoters. This study reports the cloning and characterization of a second member of the ZBP family that also binds GC boxes. ZBP-99 contains four Krüppel-type zinc fingers that collectively share 91% amino acid sequence similarity and 79% sequence identity with those found in ZBP-89. In addition, there are highly conserved amino acid sequences in the carboxy-terminal segments of the two genes. In spite of their structural similarities, the two proteins are encoded at distinct loci, ZBP-89 on chromosome 3q21 and ZBP-99 on 1q32.1. The predicted open reading frame of ZBP-99 cDNA encodes a 99-kDa protein. Electrophoretic mobility shift assays showed that ZBP-99 protein specifically binds to the GC-rich promoter elements of gastrin and ODC genes. Northern blot analysis showed that a major ZBP-99 transcript of 5.6 kb is expressed ubiquitously at low levels, with elevated expression levels in placenta and in adult kidney, liver, and lymphocytes. Cotransfection of AGS gastric adenocarcinoma and HT-29 colon adenocarcinoma cells with a ZBP-99 expression construct and with an ODC reporter construct show that ZBP-99 repressed basal expression in the two cell lines by 80 and 60%, respectively. Collectively, the data suggest that ZBP-99 binds GC-rich promoters and may complement the activities mediated by ZBP-89.