A novel transcription factor and two members of the Sp 1 multigene family regulate the activity of the alpha 2 (VI) collagen promoter

For a better understanding of the processes that lead to the activation or inhibition of type VI collagen synthesis, we have identified and characterized the cis-acting elements of the chicken alpha 2 (VI) collagen promoter. This promoter encompasses four sites, termed S1, S2, X and S3, which interact with nuclear factors. Sites S1, S2 and S3 are each recognized by the same two proteins that belong to the Sp 1 multigene family. Site X appears to interact with a novel transcription factor of 43 kDa. When a fragment containing all four of the elements is placed in front of a reporter gene, the resulting construct is able to induce a high level of transcription in chicken fibroblasts. As soon as a single element is deleted from this construct, the activity decreases drastically. Thus, the four elements are essential for the transcriptional activation of the alpha 2 (VI) collagen gene.