Structural and functional characterization of the human and mouse fibulin-1 gene promoters: role of Sp1 and Sp3.
Fibulin-1 is a multifunctional extracellular protein involved in diverse biological processes including cardiovascular development, haemostasis and cancer. To investigate the transcriptional regulation of the gene encoding fibulin-1 we cloned and analysed about 4.0 kb of the 5'-flanking regions of both the human and mouse fibulin-1 genes. The human and mouse fibulin-1 promoters share little sequence similarity except for a short region of approx. 150-170 bp immediately upstream of the translation start site. The conserved region contains a TATA-like sequence (ATAATT) and multiple consensus binding sites for Sp1 and activator protein 2 (AP-2). That the short conserved region in each gene confers basal promoter activity is demonstrated by transient transfections of promoter deletion constructs for both the human and mouse genes into cells that express fibulin-1 constitutively. Co-transfections of promoter constructs with expression plasmids for Sp1, Sp3 and Sp4 into Drosophila SL2 cells indicate that Sp1 and Sp3 are essential for transcriptional activation and that these two factors act synergistically. Electrophoretic mobility-shift assays show that Sp1 and Sp3, but not AP-2, bind to the basal promoter of the human fibulin-1 gene. The results demonstrate the functional importance of Sp1 and Sp3 in regulating the expression of the fibulin-1 gene.
Castoldi
Mirco
M
Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA 19107, U.S.A.
Chu
Mon-Li
ML
D000818:Animals; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000502:physiology*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012689:Sequence Homology, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000502:physiology*; D051705:Sp3 Transcription Factor; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic
D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; C497122:Sp3 protein, mouse; D014157:Transcription Factors; C060820:fibulin; D051705:Sp3 Transcription Factor