POSITIVE REGULATION OF HUMAN ALPHA-1(I) COLLAGEN PROMOTER ACTIVITY BYTRANSCRIPTION FACTOR SP1

Analysis of the regulatory promoter region of the human alpha 1(I) col lagen-encoding gene (COL1A1) gene indicated the presence of G+C-rich s equence elements that are potential binding sites for the transcriptio n factor Spl. As a step toward understanding transcriptional regulatio n of the human COL1A1, we examined Spl binding in the promoter region using DNase I footprinting, and analyzed the effect of Spl expression on COL1A1 promoter activity in transiently transfected Drosophila mela nogaster cells in vivo. The results indicated that recombinant human S pl interacted specifically with two G+C-rich sequences within the COL1 A1 promoter. Binding of factors in nuclear extracts prepared from huma n dermal fibroblasts to a 22-nucleotide deoxyribonucleotide (oligo) sp anning the 5' G+C-rich sequence required Zn2+, and was abolished by ex cess Spl consensus binding site oligos, or by anti-Spl antibodies. Stu dies in which a series of progressively 5'-deleted COL1A1 promoter::ca t constructs were co-expressed with an Spl expression plasmid in a cel lular background devoid of Spl homology demonstrated that Spl markedly enhanced the COL1A1 promoter activity. These results suggest that the transcriptional activity of the human COL1A1 can be positively regula ted by Sp1.