Egr-1 and Sp1 interact functionally with the 5-lipoxygenase promoter and its naturally occurring mutants.
5-Lipoxygenase (5-LO), an enzyme essential for the formation of leukotrienes, is functionally modulated by a number of mechanisms, including transcriptional controls. The 5-LO promoter has a unique G+C-rich sequence, located between 176 and 147 base pairs upstream of the ATG translation start site, which contains five tandem Sp1 (a zinc-finger transcription factor) consensus binding sites overlapping five tandem early growth response protein 1 (Egr-1), a zinc-finger transcription factor, consensus binding sites. A family of naturally occurring mutations has been identified that consists of additions or deletions of these binding sites. The role of these overlapping Sp1/Egr-1 sites in the regulation of 5-LO transcription and the effects of these mutations on transcriptional regulatory mechanisms are unknown. We now show that Sp1 and Egr-1 bind specifically to the G+C-rich promoter sequence using in vitro deoxyribonuclease I footprinting. Both Sp1 and Egr-1 activate 5-LO promoter-reporter constructs in a minimally active drosophila SL2 cotransfection system, and the G+C-rich sequence is involved in this process. Moreover, studies comparing mutant promoter function indicate that both Sp1 and Egr-1 trans-activation are proportional to the number of Sp1/Egr-1 consensus binding sites within the G+C-rich sequence. It is possible that basal and inducible 5-LO gene transcriptions are mediated by an interplay of Sp1, Egr-1, and other transcription factors within the G+C-rich promoter region, and the naturally occurring mutations alter transcription by modifying their trans-activation potential.
Pulmonary and Critical Care Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.
E S
ES
Silverman
J
J
Du
G T
GT
De Sanctis
O
O
Rådmark
B
B
Samuelsson
J M
JM
Drazen
T
T
Collins
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000235:genetics*; D001665:Binding Sites; D002460:Cell Line; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004330:Drosophila; D009154:Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D001094:Arachidonate 5-Lipoxygenase