Identification of novel promoter and repressor elements in the 5'-flanking regions of the rat insulin-like growth factor-I gene.
Although the major endocrine source of insulin-like growth factor-I (IGF-I) is the liver, little is known about IGF-I transcriptional mechanisms in this tissue. To evaluate the role of cis-regulatory elements, rat hepatocytes in primary culture were transfected with DNA constructs containing IGF-I 5'flanking sequences, fused to a luciferase reporter. We demonstrate the presence of a novel promoter approximately 0.5 kb upstream from exon 1 transcription initiation sites, together with a repressor element in this region, and a downstream repressor element which can modulate the activity of both endogenous and heterologous promoters.
Huang
S
S
Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322.
Thulé
P M
PM
Phillips
L S
LS
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D016384:Consensus Sequence; D005091:Exons; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000235:genetics*; D008099:Liver / Q000378:metabolism*; D008156:Luciferases / Q000096:biosynthesis; D008297:Male; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection
D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D007334:Insulin-Like Growth Factor I; D008156:Luciferases