Functional analysis of a newly identified TAAT-box of the rat insulin-II gene promoter.
Transcriptional regulation of insulin gene expression is achieved by an interplay of tissue-specific and ubiquitous cis- and trans-acting elements. E-box like motifs and TAAT-motifs were shown to play a crucial role in initiating insulin gene transcription. Studying the AT-rich region of the rat insulin-II promoter between nucleotides -212 and -196, we observed a base difference at -211, an adenosine instead of a cytidine, compared to the previously reported sequence (EMBL Accession No. J00748). Sequence analysis of promoter fragments from different rat strains showed that adenosine at position -211 represents the wild type (EMBL Accession No. X82162). This base exchange leads to the formation of an additional TAAT-motif, i.e. TAAT3, at the complementary DNA strand directly upstream of the previously studied TAAT2 motif, formerly named CT-2. Here we show that the newly identified motif TAAT3 is involved in (i) transcriptional control in vivo, (ii) in vitro DNA/protein interactions, and that (iii) TAAT1, TAAT2 and TAAT3 are binding sites for the homeodomain-containing factor IPF-1.
Leibiger
I B
IB
Institut für Biochemie, Medizinische Fakultät, Ernst-Moritz-Arndt Universität, Greifswald, Germany.
Schwarz
T
T
Leibiger
B
B
Walther
R
R
D000241:Adenosine; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins; D007328:Insulin / Q000235:genetics*; D007340:Insulinoma; D008969:Molecular Sequence Data; D010190:Pancreatic Neoplasms; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D018398:Homeodomain Proteins; D007328:Insulin; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D004247:DNA; D000241:Adenosine