| First Author | Liu Y | Year | 2001 |
| Journal | J Biol Chem | Volume | 276 |
| Issue | 21 | Pages | 17985-93 |
| PubMed ID | 11279116 | Mgi Jnum | J:116355 |
| Mgi Id | MGI:3694141 | Doi | 10.1074/jbc.M100678200 |
| Citation | Liu Y, et al. (2001) DNA binding and transcriptional activation by a PDX1.PBX1b.MEIS2b trimer and cooperation with a pancreas-specific basic helix-loop-helix complex. J Biol Chem 276(21):17985-93 |
| abstractText | In pancreatic acinar cells, the HOX-like factor PDX1 acts as part of a trimeric complex with two TALE class homeodomain factors, PBX1b and MEIS2b. The complex binds to overlapping half-sites for PDX1 and PBX. The trimeric complex activates transcription in cells to a level about an order of magnitude greater than PDX1 alone. The N-terminal PDX1 activation domain is required for detectable transcriptional activity of the complex, even though PDX1 truncations bearing only the PDX1 C-terminal homeodomain and pentapeptide motifs can still participate in forming the trimeric complex. The conserved N-terminal PBC-B domain of PBX, as well as its homeodomain, is required for both complex formation and transcriptional activity. Only the N-terminal region of MEIS2, including the conserved MEIS domains, is required for formation of a trimer on DNA and transcriptional activity: the MEIS homeodomain is dispensable. The activity of the pancreas-specific ELA1 enhancer requires the cooperation of the trimer-binding element and a nearby element that binds the pancreatic transcription factor PTF1. We show that the PDX1. PBX1b.MEIS2b complex cooperates with the PTF1 basic helix-loop-helix complex to activate an ELA1 minienhancer in HeLa cells and that this cooperation requires all three homeoprotein subunits, including the PDX1 activation domain. |
