Molecular cloning and functional analysis of the promoter of the XXXX squalene synthase gene.

@entity1 @entity5068 @entity2036 @entity3150 @entity1404 @entity3419 @entity157
We have cloned and characterized the 5'-flanking region of the gene encoding @entity1 squalene synthase. We report here the promoter activity of successively 5'-truncated sections of a 1 kilobase of this region by fusing it to the coding region of a luciferase reporter gene. DNA segments of 200 base pairs (bp) 5' to the transcription start site, as determined by primer extension analysis, show a strong promoter effect on the expression of the luciferase chimeric gene and a high response to the presence of @entity3150 when transiently transfected into the @entity1 @entity157 cell line HepG2 or to the hamster-derived CHO-K1 cells. An approximately 50-fold induction of luciferase activity, in the absence of @entity3150 , was observed in transiently transfected HepG2 cells for fusion constructs containing sections of 200, 459, and 934 bp of the putative @entity1 squalene synthase promoter. Loss of promoter activity and response to @entity3150 was localized to a 69-bp section located 131 @entity2036 5' to the transcription start site. Sequence analysis of this region showed that it contained a @entity5068 regulatory element 1 (SRE-1) previously identified in other @entity5068 regulated genes (Smith, J. R., Osborne, T. F., Brown, M. S., Goldstein, J. L., and Gil, G. (1988). J. Biol. Chem. 263, 18480-18487) and two potential NF-1 binding sites. Additional CCAAT box, SRE-1 element, and two @entity3419 sites were identified 3' to this section. Sequences within this 69-bp DNA, including the SRE-1 cis-acting element, show strong binding to the purified nuclear transcription factor @entity1404 (Tonzonoz, P., Kim, J. B., Graves, R. A., and Spiegelman B. M. (1993) Mol. Cell Biol. 13, 4753-4759) by mobility shift assay and footprinting analyses.
