Identification of trans-acting factors that interact with cis-acting elements present in the first nontranslated exon of the human apolipoprotein B gene.
Apolipoprotein B is the sole protein of low density lipoprotein and is produced primarily in the liver. Previously, we have identified two cis-acting elements (+20 to +40; +43 to +53) in the non-translated exon of the human apolipoprotein B gene, using DNase I footprint analysis (S. S. Chuang, H. Zhuang, S. R. Reisher, S. I. Feinstein, and H. K. Das, Biochem. Biophys. Res. Com. 215, 394-404, 1995). Wild type and mutated promoter constructs were used as templates in DNase I footprint analysis with rat liver nuclear extracts. These experiments suggest that trans-acting factors BRF-3 and BRF-4 which recognize these two footprint regions (+20 to +40; +43 to +53) respectively, act independently. In vitro-synthesized hepatocyte nuclear factors HNF-1alpha, HNF-lbeta. HNF-3alpha, and HNF-2/HNF-4 showed no specific protein/DNA interaction with these regions. DNase I footprint analysis using other DNA-binding site oligonucleotides as competitors indicated that BRF-3 and BRF-4 could be different hepatocyte nuclear factors and may contribute to the regulation of transcription of the human apolipoprotein B gene.
Chuang
S S
SS
Department of Pharmacology, University of North Texas, The Health Science Center at Fort Worth, 76107, USA.
Das
H K
HK
D000818:Animals; D001055:Apolipoproteins B / Q000096:biosynthesis* / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000378:metabolism; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I; D005091:Exons; D006801:Humans; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*
D001055:Apolipoproteins B; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors; D003850:Deoxyribonuclease I