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.