Limits...
Integrated genome-wide chromatin occupancy and expression analyses identify key myeloid pro-differentiation transcription factors repressed by Myb.

Zhao L, Glazov EA, Pattabiraman DR, Al-Owaidi F, Zhang P, Brown MA, Leo PJ, Gonda TJ - Nucleic Acids Res. (2011)

Bottom Line: Importantly, we also show that, despite being usually considered as a transactivator, Myb also functions to repress approximately half of its direct targets, including several key regulators of myeloid differentiation, such as Sfpi1 (also known as Pu.1), Runx1, Junb and Cebpb.Furthermore, our results demonstrate that interaction with p300, an established coactivator for Myb, is unexpectedly required for Myb-mediated transcriptional repression.We propose that the repression of the above mentioned key pro-differentiation factors may contribute essentially to Myb's ability to suppress differentiation and promote self-renewal, thus maintaining progenitor cells in an undifferentiated state and promoting leukemic transformation.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland Diamantina Institute, Brisbane, Queensland 4102, Australia.

ABSTRACT
To gain insight into the mechanisms by which the Myb transcription factor controls normal hematopoiesis and particularly, how it contributes to leukemogenesis, we mapped the genome-wide occupancy of Myb by chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-Seq) in ERMYB myeloid progenitor cells. By integrating the genome occupancy data with whole genome expression profiling data, we identified a Myb-regulated transcriptional program. Gene signatures for leukemia stem cells, normal hematopoietic stem/progenitor cells and myeloid development were overrepresented in 2368 Myb regulated genes. Of these, Myb bound directly near or within 793 genes. Myb directly activates some genes known critical in maintaining hematopoietic stem cells, such as Gfi1 and Cited2. Importantly, we also show that, despite being usually considered as a transactivator, Myb also functions to repress approximately half of its direct targets, including several key regulators of myeloid differentiation, such as Sfpi1 (also known as Pu.1), Runx1, Junb and Cebpb. Furthermore, our results demonstrate that interaction with p300, an established coactivator for Myb, is unexpectedly required for Myb-mediated transcriptional repression. We propose that the repression of the above mentioned key pro-differentiation factors may contribute essentially to Myb's ability to suppress differentiation and promote self-renewal, thus maintaining progenitor cells in an undifferentiated state and promoting leukemic transformation.

Show MeSH

Related in: MedlinePlus

Global identification of MBRs in vivo. (A) Both anti-ER antibody and anti-Myb sera worked in ChIP assays in ERMYB cells: the ER-Myb fusion protein occupied a known Myb binding site in Mpo promoter (Mpo -0.32 kb). B2m TSS region served as a negative control. (B) Representation of ChIP-Seq sequencing reads (raw data) across loci of two established Myb targets—Mpo and Bcl2. (Arrows) ChIP-Seq peak locations relative to TSS of the respective gene (kb). (C) Identified Myb motif shares the AACNG core binding consensus sequence with the previously reported Myb binding consensus in Transfac database. (D) Distribution of MBRs relative to the nearest TSS (kb). Regions 5′ to the TSS are indicated as negative values on the x-axis. (E) Distribution of MBRs relative to Refseq gene features.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3113568&req=5

Figure 2: Global identification of MBRs in vivo. (A) Both anti-ER antibody and anti-Myb sera worked in ChIP assays in ERMYB cells: the ER-Myb fusion protein occupied a known Myb binding site in Mpo promoter (Mpo -0.32 kb). B2m TSS region served as a negative control. (B) Representation of ChIP-Seq sequencing reads (raw data) across loci of two established Myb targets—Mpo and Bcl2. (Arrows) ChIP-Seq peak locations relative to TSS of the respective gene (kb). (C) Identified Myb motif shares the AACNG core binding consensus sequence with the previously reported Myb binding consensus in Transfac database. (D) Distribution of MBRs relative to the nearest TSS (kb). Regions 5′ to the TSS are indicated as negative values on the x-axis. (E) Distribution of MBRs relative to Refseq gene features.

Mentions: We subsequently filtered the 11 429 candidate MBRs for presence of Myb binding motif by scanning 160 bp sequences (80 bp on either side of peak summits) of candidate MBRs with the identified position weight matrix for Myb binding (Figure 2C) with a threshold of 0.8 determined empirically. The resultant list comprises 7646 high-confidence MBRs (Supplementary Table S5). We subsequently assigned each MBR to its nearest gene according to its distance to transcription start site (TSS).Figure 2.


Integrated genome-wide chromatin occupancy and expression analyses identify key myeloid pro-differentiation transcription factors repressed by Myb.

Zhao L, Glazov EA, Pattabiraman DR, Al-Owaidi F, Zhang P, Brown MA, Leo PJ, Gonda TJ - Nucleic Acids Res. (2011)

Global identification of MBRs in vivo. (A) Both anti-ER antibody and anti-Myb sera worked in ChIP assays in ERMYB cells: the ER-Myb fusion protein occupied a known Myb binding site in Mpo promoter (Mpo -0.32 kb). B2m TSS region served as a negative control. (B) Representation of ChIP-Seq sequencing reads (raw data) across loci of two established Myb targets—Mpo and Bcl2. (Arrows) ChIP-Seq peak locations relative to TSS of the respective gene (kb). (C) Identified Myb motif shares the AACNG core binding consensus sequence with the previously reported Myb binding consensus in Transfac database. (D) Distribution of MBRs relative to the nearest TSS (kb). Regions 5′ to the TSS are indicated as negative values on the x-axis. (E) Distribution of MBRs relative to Refseq gene features.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3113568&req=5

Figure 2: Global identification of MBRs in vivo. (A) Both anti-ER antibody and anti-Myb sera worked in ChIP assays in ERMYB cells: the ER-Myb fusion protein occupied a known Myb binding site in Mpo promoter (Mpo -0.32 kb). B2m TSS region served as a negative control. (B) Representation of ChIP-Seq sequencing reads (raw data) across loci of two established Myb targets—Mpo and Bcl2. (Arrows) ChIP-Seq peak locations relative to TSS of the respective gene (kb). (C) Identified Myb motif shares the AACNG core binding consensus sequence with the previously reported Myb binding consensus in Transfac database. (D) Distribution of MBRs relative to the nearest TSS (kb). Regions 5′ to the TSS are indicated as negative values on the x-axis. (E) Distribution of MBRs relative to Refseq gene features.
Mentions: We subsequently filtered the 11 429 candidate MBRs for presence of Myb binding motif by scanning 160 bp sequences (80 bp on either side of peak summits) of candidate MBRs with the identified position weight matrix for Myb binding (Figure 2C) with a threshold of 0.8 determined empirically. The resultant list comprises 7646 high-confidence MBRs (Supplementary Table S5). We subsequently assigned each MBR to its nearest gene according to its distance to transcription start site (TSS).Figure 2.

Bottom Line: Importantly, we also show that, despite being usually considered as a transactivator, Myb also functions to repress approximately half of its direct targets, including several key regulators of myeloid differentiation, such as Sfpi1 (also known as Pu.1), Runx1, Junb and Cebpb.Furthermore, our results demonstrate that interaction with p300, an established coactivator for Myb, is unexpectedly required for Myb-mediated transcriptional repression.We propose that the repression of the above mentioned key pro-differentiation factors may contribute essentially to Myb's ability to suppress differentiation and promote self-renewal, thus maintaining progenitor cells in an undifferentiated state and promoting leukemic transformation.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland Diamantina Institute, Brisbane, Queensland 4102, Australia.

ABSTRACT
To gain insight into the mechanisms by which the Myb transcription factor controls normal hematopoiesis and particularly, how it contributes to leukemogenesis, we mapped the genome-wide occupancy of Myb by chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-Seq) in ERMYB myeloid progenitor cells. By integrating the genome occupancy data with whole genome expression profiling data, we identified a Myb-regulated transcriptional program. Gene signatures for leukemia stem cells, normal hematopoietic stem/progenitor cells and myeloid development were overrepresented in 2368 Myb regulated genes. Of these, Myb bound directly near or within 793 genes. Myb directly activates some genes known critical in maintaining hematopoietic stem cells, such as Gfi1 and Cited2. Importantly, we also show that, despite being usually considered as a transactivator, Myb also functions to repress approximately half of its direct targets, including several key regulators of myeloid differentiation, such as Sfpi1 (also known as Pu.1), Runx1, Junb and Cebpb. Furthermore, our results demonstrate that interaction with p300, an established coactivator for Myb, is unexpectedly required for Myb-mediated transcriptional repression. We propose that the repression of the above mentioned key pro-differentiation factors may contribute essentially to Myb's ability to suppress differentiation and promote self-renewal, thus maintaining progenitor cells in an undifferentiated state and promoting leukemic transformation.

Show MeSH
Related in: MedlinePlus