Characterization of the promoter of human extracellular matrix metalloproteinase inducer (EMMPRIN).

Monocyte-derived macrophages play a central role in atherosclerotic lesion formation and potentially plaque destabilization by expression of matrix metalloproteinases (MMPs); however, mechanisms associated with stimulating MMP production are not clearly understood. EMMPRIN, which is expressed by human cancer cells and macrophages, present in human, mouse and rabbit atherosclerosis and noted to induce MMPs may be involved. A DNA fragment containing 1797 bp 5' upstream of the EMMPRIN gene and the transcription start site was generated by polymerase chain reaction and cloned into a luciferase reporter gene vector, pGL3-basic. The relative luciferase activities driven by this 5'-upstream fragment and a series of deletion mutants were measured in transiently transfected human and mouse macrophage THP-1 and Raw264.7 cells, respectively. A fragment 471 bp upstream of the EMMPRIN coding region was sufficient to promote transcription, while a region from -1413 to -1024 bp suppressed activity. Further deletion analysis of the 471 bp fragment indicated that a 30 bp element from -142 to -112 bp, which contains binding sites for Sp1, AP1TFII and EGR-2, was important for EMMPRIN transcription in both THP-1 and Raw264.7 macrophages. Using electrophoretic mobility shift assays, the Sp1 element within 30 bp region specifically bound Sp1 and Sp3 transcription factors. Mutation of the Sp1 element at -122 to -116 bp of the EMMPRIN promoter significantly diminished promoter activity and formation of DNA-nuclear protein complex. Transient expression of Sp1 and/or Sp3 transcription factors in insect cells lacking the Sp family of transcription factors, stimulated EMMPRIN promoter activity in a synergistic manner. Together, these results indicate that both Sp1 and Sp3 associate with the functional Sp1 element on the EMMPRIN promoter and cooperate in the regulation of EMMPRIN gene expression in macrophages.