Identification of novel, functional genetic variants in the human matrix metalloproteinase-2 gene - Role of Sp1 in allele-specific transcriptional regulation

Matrix metalloproteinase-2 (MMP-8) is an enzyme with proteolytic activity a gainst matrix and nonmatrix proteins, particularly basement membrane consti tuents. Thus, any naturally occurring genetic variants that directly affect gene expression and/or protein function would be expected to impact on pro gression of pathological processes involving tissue remodeling. We scanned a a-kilobase pair promoter region and all 13 exons of the human MMP-2 gene, from a panel of 32 individuals, and we identified the position, nature, an d relative allele frequencies of 15 variant loci as follows: 6 in the promo ter, 1 in the 5'-untranslated region, 6 in the coding region, 1 in intronic sequence, and 1 in the 3'-untranslated region. The majority of coding regi on polymorphisms resulted in synonymous substitutions, whereas three promot er variants (at -1306, -790, and +220) mapped onto cis-acting elements, We functionally characterized all promoter variants by transient transfection experiments with 293, RAW264.7, and A10 cells. The common C --> T transitio n at -1306 (allele frequency 0.26), which disrupts an Spl-type promoter sit e (CCACC box), displayed a strikingly lower promoter activity with the T al lele, Electrophoretic mobility shift assays confirmed that these difference s in allelic expression were attributable to abolition of Spl binding. Thes e data suggest that this common functional genetic variant influences MMP-2 gene transcription in an allele-specific manner and is therefore an import ant candidate to test for association in a wide spectrum of pathologies for which a role for MMP-8 is implicated, including atherogenesis and tumor in vasion and metastasis.