title: Transcriptional regulatory networks downstream of TAL1/SCL in T-cell acute lymphoblastic leukemia.
abstract: Aberrant expression of 1 or more transcription factor oncogenes is a critical component of the molecular pathogenesis of human T-cell acute lymphoblastic leukemia (T-ALL); however, oncogenic transcriptional programs downstream of T-ALL oncogenes are mostly unknown. TAL1/SCL is a basic helix-loop-helix (bHLH) transcription factor oncogene aberrantly expressed in 60% of human T-ALLs. We used chromatin immunoprecipitation (ChIP) on chip to identify 71 direct transcriptional targets of TAL1/SCL. Promoters occupied by TAL1 were also frequently bound by the class I bHLH proteins E2A and HEB, suggesting that TAL1/E2A as well as TAL1/HEB heterodimers play a role in transformation of T-cell precursors. Using RNA interference, we demonstrated that TAL1 is required for the maintenance of the leukemic phenotype in Jurkat cells and showed that TAL1 binding can be associated with either repression or activation of genes whose promoters occupied by TAL1, E2A, and HEB. In addition, oligonucleotide microarray analysis of RNA from 47 primary T-ALL samples showed specific expression signatures involving TAL1 targets in TAL1-expressing compared with -nonexpressing human T-ALLs. Our results indicate that TAL1 may act as a bifunctional transcriptional regulator (activator and repressor) at the top of a complex regulatory network that disrupts normal T-cell homeostasis and contributes to leukemogenesis.
authors.affiliation: Institute for Cancer Genetics, Columbia University, 1150 St Nicholas Ave, New York, NY 10032, USA.
authors.forename: Teresa
authors.initials: T
authors.lastname: Palomero
authors.forename: Duncan T
authors.initials: DT
authors.lastname: Odom
authors.forename: Jennifer
authors.initials: J
authors.lastname: O'Neil
authors.forename: Adolfo A
authors.initials: AA
authors.lastname: Ferrando
authors.forename: Adam
authors.initials: A
authors.lastname: Margolin
authors.forename: Donna S
authors.initials: DS
authors.lastname: Neuberg
authors.forename: Stuart S
authors.initials: SS
authors.lastname: Winter
authors.forename: Richard S
authors.initials: RS
authors.lastname: Larson
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: X Shirley
authors.initials: XS
authors.lastname: Liu
authors.forename: Richard A
authors.initials: RA
authors.lastname: Young
authors.forename: A Thomas
authors.initials: AT
authors.lastname: Look
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D002471:Cell Transformation, Neoplastic; D047369:Chromatin Immunoprecipitation; D019281:Dimerization; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D019169:Jurkat Cells; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000209:etiology / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014158:Transcription, Genetic
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D011518:Proto-Oncogene Proteins; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; C407909:TCF3 protein, human; C067143:TAL1 protein, human; C073366:TCF12 protein, human