Tal1/SCL binding to pericentromeric DNA represses transcription.
Tal1/SCL is a basic helix-loop-helix transcription factor critical for normal hematopoiesis. To understand the mechanisms underlying transcriptional regulation by Tal1/SCL, we combined an in vitro DNA binding strategy and an in vivo chromatin immunoprecipitation analysis to search for Tal1/SCL target regions in K562 erythroleukemia cells. A 0.4-kb genomic DNA clone containing two Tal1/SCL binding E-boxes and GATA- and SATB1-binding motifs (EEGS) was identified that localized to the pericentromeric region with high homology to satellite 2 DNA. Pericentric DNA is related to heterochromatin and gene inactivation. We found that Tal1/SCL could complex with the histone H3 lysine 9 (H3K9)-specific methyltransferase Suv39H1. Binding of Tal1/SCL to EEGS chromatin correlated with hypermethylation of H3K9 and the association of heterochromatin protein HP1 to this region. In Rep4 reporter gene assays, EEGS affected repression in a manner dependent on the expression level of Tal1/SCL that was accompanied by increased H3K9 methylation in chromatin associated with EEGS and a linked promoter. A specific histone deacetylase inhibitor, trichostatin A, relieved Tal1/SCL-mediated repression by EEGS. In addition, SATB1 bound EEGS chromatin and promoted Tal1/SCL EEGS-dependent repression. We expand the list of potential interacting partners for Tal1/SCL by demonstrating direct associations of Tal1/SCL with SATB1 and with Suv39H1. These results reveal a novel mechanism of action for Tal1/SCL and implicate heterochromatin-like silencing via a cis-acting binding motif for transcriptional repression.
Wen
Jie
J
Molecular Medicine Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Huang
Suming
S
Pack
Svetlana D
SD
Yu
Xiaobing
X
Brandt
Stephen J
SJ
Noguchi
Constance Tom
CT
D020816:Amino Acid Motifs; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D002875:Chromosomes / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D019175:DNA Methylation; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D017930:Genes, Reporter; D006367:HeLa Cells; D006570:Heterochromatin / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted; D017404:In Situ Hybridization, Fluorescence; D020014:K562 Cells; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic
D051792:Basic Helix-Loop-Helix Proteins; D002843:Chromatin; D004247:DNA; D017931:DNA Primers; D004268:DNA-Binding Proteins; D006570:Heterochromatin; D006657:Histones; D006877:Hydroxamic Acids; D011518:Proto-Oncogene Proteins; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; C067143:TAL1 protein, human; C012589:trichostatin A