These data suggest that this functional genetic variation influences gelatinase B gene promoter activity in an allele-specific manner and has an effect on atherosclerotic phenotype.

No abstract

There is a common polymorphism in the promoter sequence of the human stromelysin-1 gene, with one allele having a run of six adenosines (6A) and the other five adenosines (5A). We have previously reported, in a 3-year follow-up study of patients with coronary atherosclerosis, that those patients who are homozygous for the 6A allele show a more rapid progression of the disease. In this study, we have investigated whether the 5A/6A promoter polymorphism plays a role in the regulation of stromelysin-1 gene expression. In transient transfection experiments, a stromelysin-1 promoter construct with 6A at the polymorphic site was found to express less of the chloramphenicol acetyltransferase reporter gene than a construct containing 5A. Electrophoretic mobility shift assay and DNase I footprinting revealed the interaction of one or more nuclear protein(s) with the DNA sequence at the 5A/6A polymorphic site. The binding of one of the nucleoprotein factors was more readily detectable with an oligonucleotide probe corresponding to the 6A allele as compared with a probe corresponding to the 5A allele. Replacing the core binding sequence with a random DNA sequence abolished the interaction between the nuclear protein(s) and the probe and also increased reporter gene expression in transiently transfected cells. Thus, the common 5A/6A polymorphism of the human stromelysin-1 promoter appears to play an important role in regulating stromelysin-1 gene expression and may be involved in the progression of coronary heart disease.Stromelysin-1 is a key member of the matrix metalloproteinase (MMP) 1 family, with a broad substrate specificity. It can degrade types II, IV, and IX collagen, proteoglycans, laminin, fibronectin, gelatins, and elastin (1-3). In addition, stromelysin-1 can also activate other MMPs such as collagenase, matrilysin, and gelatinase B, rendering stromelysin-1 crucial in connective tissue remodeling (4 -6). Expression of stromelysin-1 is primarily regulated at the level of transcription, where the promoter of the gene responds to various stimuli, including growth factors, cytokines, tumor promoters, and oncogene products (7-10). The regulatory effects of such stimuli are mediated through a number of cis-elements located in the stromelysin-1 promoter. For instance, the activator protein-1 binding site at positions Ϫ63 to Ϫ70 is necessary for the basal expression of the gene and is also involved in interleukin-1 induction (11-13). A promoter element located between Ϫ1218 and Ϫ1202 is responsible for the induction of stromelysin-1 expression by platelet-derived growth factor B/B (14, 15), whereas three sequences that share strong homology with the glucocorticoid-responsive consensus element are likely to be involved in the dexamethasone suppression (16).Over the last few years, MMPs have been implicated in the connective tissue remodeling during atherogenesis (17)(18)(19)(20)(21)(22). By in situ mRNA hybridization, we originally demonstrated the presence of stromelysin-1 in coronary atherosclerotic plaques (18). E...

The stromelysins are members of a family of extracellular matrix metalloproteinases. These enzymes may erode the connective tissue in atherosclerotic plaques, leading to fissuring and acute thrombotic events. Cell-specific stromelysin expression in human atherosclerotic plaques was studied by in situ hybridization and Immunocytochemistry. Sections were taken from nine coronary arteries: eight with wellestablished plaques and one normal. Unambiguous signals were seen in five plaques, two were inconclusive, and the remaining sample was negative, as was the normal coronary artery. Stromelysin mRNA transcripts were localized to isolated individual cells, some ofwhich were smooth muscle, in the plaque cap, intima, and adventitia, but not the media. Expression was also seen in large clusters of macrophages that contained intracellular lipid deposits. The isolated expression of stromelysin by smooth muscle cells may reflect local connective tissue remodeling associated with growth and the formation of the plaque, whereas the more extensive expression associated with macrophages may be of greater pathological sinficance, contributing to the destabilization of the extracellular matrix and eventual plaque rupture.The morphology of atheromatous plaques ranges from solid fibrous structures to those with a substantial lipid core, covered by a fibrous cap (1). Fibrous plaques are essentially stable lesions, but the "soft," lipid-laden plaques are prone to intimal tearing (fissuring), the commonest event initiating coronary thrombosis (2). Migration of macrophages and T cells into soft plaques has been observed, and the lesion has all the hallmarks of an inflammatory response (3). As macrophages produce a number of potent proteases (4), their presence in large numbers may lead to plaque rupture as a result of destabilization of the supporting connective tissue matrix. Alternatively, cytokines and growth factors secreted by activated macrophages (5) may induce neighboring cells, such as smooth muscle cells, to erode the collagen and elastin that forms the framework of the plaque.Stromelysins are a group of enzymes within the mammalian tissue metalloproteinase (MP) family. These proteinases are generally characterized by their ability to function at neutral pH, the need to bind Zn2+ as a cofactor, and their secretion in a latent form requiring activation for proteolytic activity (6, 7). As a group, the tissue MPs have the capacity to completely degrade all extracellular matrix macromolecules, playing a major role in both physiological and pathological events that lead to matrix degradation. Stromelysins are produced by a variety ofcell types, have a broad substrate specificity, and can degrade most of the constituents of the extracellular matrix within atherosclerotic plaques. Stromelysins 1 and 2 have an identical spectrum of activity (reviewed in refs. 6 and 8), but stromelysin 1 is more potent (9). The principal substrate is proteoglycan core protein, but these enzymes also degrade nonhelical regions of types II, IV,...

Plasminogen activator inhibitor-1 (PAI-1), a rapid inhibitor of tissue-type plasminogen activator, has been shown to be an independent risk factor for recurrent myocardial infarction (MI) at a young age. To investigate whether genetic variation in the PAI-1 gene is affecting plasma PAI-1 levels, a sample of 145 patients with an MI before the age of 45 years was genotyped for two polymorphisms at the PAI-1 locus, together with a sample of 95 healthy individuals of a similar age. All individuals were measured for plasma PAI-1 levels as well as for other fibrinolytic and metabolic risk indicators. A HindlU restriction fragment length polymorphism (RFLP) was used in this study in conjunction with a previously unreported eight-allele dinucleotide repeat polymorphism at the PAI-1 locus. The dinucleotide repeat polymorphism and HindUl RFLP were in strong linkage disequilibrium. There was no difference in the frequency of alleles of either polymorphism between patient and control groups. However, the smaller dinucleotide repeat alleles were significantly associated (p=0.03) with higher plasma PAI-1 levels in the patient sample. This association was also apparent in the control sample but not at significant levels. Differences in regression coefficients for the effect of triglycerides on plasma PAI-1 levels suggest that triglyceride regulation of PAI-1 is genotype specific Our data suggest that genetic variation at this locus contributes to between-individual differences in the level of plasma PAI-1, which is important in fibrinolysis and the pathogenesis of MI. (Arteriosclerosis and Thrombosis 1991;ll: [183][184][185][186][187][188][189][190]