| First Author | Horstmann S | Year | 2000 |
| Journal | Oncogene | Volume | 19 |
| Issue | 48 | Pages | 5428-34 |
| PubMed ID | 11114719 | Mgi Jnum | J:65983 |
| Mgi Id | MGI:1927693 | Doi | 10.1038/sj.onc.1203937 |
| Citation | Horstmann S, et al. (2000) An alternatively spliced isoform of B-Myb is a transcriptional inhibitor. Oncogene 19(48):5428-34 |
| abstractText | B-Myb is a highly conserved member of the Myb transcription factor family. The primary transcript of the B-myb gene is spliced alternatively in two mRNAs which either contain or lack a sequence corresponding to the so-called exon 9A of c-myb. Recent studies showed that full-length B-Myb containing the exon 9A encoded amino acids is a cell cycle regulated transcription factor whose activity is stimulated by cyclin A/Cdk 2-dependent phosphorylation at the carboxyl-terminus of B-Myb. We have now investigated in more detail the transactivation potential of the shorter isoform of B-Myb lacking exon 9A. Here, we show that B-Myb lacking exon 9A has no transactivation activity even in the presence of cyclin A. This inactivity of the shorter isoform of B-Myb is not due an improper subcelluar localization. Our work suggests that B-Myb lacking exon 9A may act as an inhibitor for full-length B-Myb mediated transactivation. Furthermore, by analysing the transactivation potential of Gal4/B-Myb fusion proteins we have identified the amino-terminal part of the exon 9A as the principal transactivation domain of full-length B-Myb. The results presented here demonstrate that B-myb encodes both an activator and an inhibitor of transcription and, thus, reveal an additional level of regulation of B-Myb activity beside the known cyclin dependent mechanisms. |
