DIFFERENTIATION-SPECIFIC ELEMENT-BINDING PROTEIN (DSEB) BINDS TO A DEFINED ELEMENT IN THE PROMOTER OF THE ANGIOTENSINOGEN GENE REQUIRED FORTHE IRREVERSIBLE INDUCTION OF GENE-EXPRESSION DURING DIFFERENTIATION OF 3T3-L1 ADIPOBLASTS TO ADIPOCYTES

The differentiation-specific element (DSE) is a cis-acting transcripti onal element located at nucleotide -1000 in the 5'-flanking promoter o f the angiotensinogen gene. It is required for the irreversible and su stained increase in transcription of the angiotensinogen gene that occ urs during differentiation of 3T3-L1 adipoblasts into adipocytes induc ed by a 3-day hormonal pulse. We report here the cloning of 3T3-L1 adi pocyte cDNA encoding a 150 kilodalton protein designated Differentiati on Specific Element Binding Protein (DSEB) that exhibits sequence-spec ific binding to a DSE oligonucleotide. Two DSEB mRNAs (3.6 and 4.2 kil obases) are observed in adipose, brain, kidney, testis, liver, and lun g. Both DSEB mRNA and protein are induced during, and remain elevated after, 3T3-L1 cell adipogenesis. Analysis of adipoblasts by immunocyto chemistry with an antiserum directed to bacterial expressed DSEB revea ls that DSEB is localized to the nucleus and is induced during differe ntiation. DNA-binding assays show that binding is specific and exhibit s high affinity and specificity for the DSE. Deletional analyses of ba cterial expressed recombinant DSEB identifies a DNA-binding domain of 120 amino acids that contains two predicted helical regions. A sequenc e of 72 amino acids within the DNA-binding domain of DSEB is 60% ident ical to domains found in the sequences of several bacterial ligases. F urther, DSEB is homologous to several proteins reported recently that are proposed to be a component(s) of the DNA replication-C complex rai sing the possibility that DSEB may be both a transcription factor and a DNA-replication factor.