p300 functions as a transcriptional coactivator for the TAL1/SCL oncoprotein.

Huang S, Qiu Y, Stein RW, Brandt SJ
Oncogene. 1999 18 (35): 4958-67

PMID: 10490830 · DOI:10.1038/sj.onc.1202889

Activation of the TAL1 (or SCL) gene, originally identified through its involvement by a recurrent chromosomal translocation, is the most frequent gain-of-function mutation recognized in T-cell acute lymphoblastic leukemia (T-ALL). The TAL1 proteins contain a basic helix - loop - helix (bHLH) motif characteristic of a large family of transcription factors that control transcription from an E box target element as heterodimers with the E2A- and HEB-encoded gene products. Gene knockout studies in mice indicate that this transcription factor is required for embryonic and adult hematopoiesis, and considerable evidence suggests it has specific functions in terminal erythroid differentiation. We investigated whether the broadly expressed nuclear protein p300, known to function as a coactivator for other bHLH proteins involved in cellular differentiation, also interacts with TAL1. p300 was found to coimmunoprecipitate with Tal1 in extracts from murine erythroleukemia (MEL) cells induced to differentiate with dimethylsulfoxide (DMSO), and p300 and Tal1 were observed in a common E box DNA-binding complex in extracts from differentiating MEL cells. p300 also interacted with Tal1 in protein pulldown assays, suggesting this was a direct interaction. Finally, p300 augmented transcription by Tal1 from an E box-containing promoter and by a GAL4-Tal1 fusion from a promoter containing the GAL4 DNA-binding element. Deletion analysis identified the bHLH domain of Tal1 and amino-terminal sequences of p300 as necessary for p300-stimulated transactivation and Tal1-p300 interaction in vitro. These results indicate that recruitment of the transcriptional coactivator p300 can positively regulate TAL1-directed gene expression. The dependence of their interaction in MEL cells on addition of a differentiation inducer suggests, further, that this TAL1-p300 complex may have an important role in terminal erythroid differentiation.

MeSH Terms (24)

3T3 Cells Animals Basic Helix-Loop-Helix Transcription Factors Cell Differentiation Dimerization Dimethyl Sulfoxide DNA DNA-Binding Proteins E1A-Associated p300 Protein Humans Mice Nuclear Proteins Precipitin Tests Promoter Regions, Genetic Protein Binding Proto-Oncogene Proteins Recombinant Fusion Proteins Response Elements Sequence Deletion T-Cell Acute Lymphocytic Leukemia Protein 1 Trans-Activators Transcriptional Activation Transcription Factors Tumor Cells, Cultured

Connections (2)

This publication is referenced by other Labnodes entities:

Links