Genome-wide investigation of in vivo EGR-1 binding sites in monocytic differentiation.
BACKGROUND
Immediate early genes are considered to play important roles in dynamic gene regulatory networks following exposure to appropriate stimuli. One of the immediate early genes, early growth response gene 1 (EGR-1), has been implicated in differentiation of human monoblastoma cells along the monocytic commitment following treatment with phorbol ester. EGR-1 has been thought to work as a modifier of monopoiesis, but the precise function of EGR-1 in monocytic differentiation has not been fully elucidated.


RESULTS
We performed the first genome-wide analysis of EGR-1 binding sites by chromatin immunoprecipitation with promoter array (ChIP-chip) and identified EGR-1 target sites in differentiating THP-1 cells. By combining the results with previously reported FANTOM4 data, we found that EGR-1 binding sites highly co-localized with CpG islands, acetylated histone H3 lysine 9 binding sites, and CAGE tag clusters. Gene Ontology (GO) analysis revealed enriched terms, including binding of molecules, in EGR-1 target genes. In addition, comparison with gene expression profiling data showed that EGR-1 binding influenced gene expression. Moreover, observation of in vivo occupancy changes of DNA binding proteins following PMA stimulation indicated that SP1 binding occupancies were dramatically changed near EGR-1 binding sites.


CONCLUSIONS
We conclude that EGR-1 mainly recognizes GC-rich consensus sequences in promoters of active genes. GO analysis and gene expression profiling data confirm that EGR-1 is involved in initiation of information transmission in cell events. The observations of in vivo occupancy changes of EGR-1 and SP1 suggest that several types of interplay between EGR-1 and other proteins result in multiple responses to EGR-1 downstream genes.
RIKEN Omics Science Center, RIKEN Yokohama Institute 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
Atsutaka
A
Kubosaki
Yasuhiro
Y
Tomaru
Michihira
M
Tagami
Erik
E
Arner
Hisashi
H
Miura
Takahiro
T
Suzuki
Masanori
M
Suzuki
Harukazu
H
Suzuki
Yoshihide
Y
Hayashizaki
D000107:Acetylation; D001665:Binding Sites / Q000235:genetics; D015153:Blotting, Western; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands / Q000235:genetics; D051766:Early Growth Response Protein 1 / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D015894:Genome, Human / Q000235:genetics*; D006657:Histones / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D006657:Histones; D034741:RNA, Small Interfering; D016329:Sp1 Transcription Factor; D008239:Lysine; D013755:Tetradecanoylphorbol Acetate