| 1. |
- Hosokawa, Hiroyuki, et al.
(författare)
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Bcl11b sets pro-T cell fate by site-specific cofactor recruitment and by repressing Id2 and Zbtb16
- 2018
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Ingår i: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 19:12, s. 1427-1440
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Tidskriftsartikel (refereegranskat)abstract
- Multipotent progenitor cells confirm their T cell–lineage identity in the CD4–CD8– double-negative (DN) pro-T cell DN2 stages, when expression of the essential transcription factor Bcl11b begins. In vivo and in vitro stage-specific deletions globally identified Bcl11b-controlled target genes in pro-T cells. Proteomics analysis revealed that Bcl11b associated with multiple cofactors and that its direct action was needed to recruit those cofactors to selective target sites. Regions near functionally regulated target genes showed enrichment for those sites of Bcl11b-dependent recruitment of cofactors, and deletion of individual cofactors relieved the repression of many genes normally repressed by Bcl11b. Runx1 collaborated with Bcl11b most frequently for both activation and repression. In parallel, Bcl11b indirectly regulated a subset of target genes by a gene network circuit via the transcription inhibitor Id2 (encoded by Id2) and transcription factor PLZF (encoded by Zbtb16); Id2 and Zbtb16 were directly repressed by Bcl11b, and Id2 and PLZF controlled distinct alternative programs. Thus, our study defines the molecular basis of direct and indirect Bcl11b actions that promote T cell identity and block alternative potentials.
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| 2. |
- Hosokawa, Hiroyuki, et al.
(författare)
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Transcription Factor PU.1 Represses and Activates Gene Expression in Early T Cells by Redirecting Partner Transcription Factor Binding
- 2018
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Ingår i: Immunity. - : Elsevier BV. - 1074-7613. ; 48:6, s. 7-1134
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Tidskriftsartikel (refereegranskat)abstract
- Transcription factors normally regulate gene expression through their action at sites where they bind to DNA. However, the balance of activating and repressive functions that a transcription factor can mediate is not completely understood. Here, we showed that the transcription factor PU.1 regulated gene expression in early T cell development both by recruiting partner transcription factors to its own binding sites and by depleting them from the binding sites that they preferred when PU.1 was absent. The removal of partner factors Satb1 and Runx1 occurred primarily from sites where PU.1 itself did not bind. Genes linked to sites of partner factor “theft” were enriched for genes that PU.1 represses despite lack of binding, both in a model cell line system and in normal T cell development. Thus, system-level competitive recruitment dynamics permit PU.1 to affect gene expression both through its own target sites and through action at a distance. Transcription factors regulate target genes via sequence-specific DNA binding. They may collaborate when bound together, but are assumed to be independent at sites where they bind alone. Hosokawa, Ungerbäck et al. show that PU.1 broadly shifts the genome-wide site choice of Runx1 DNA binding, enabling PU.1 to repress some target genes at a distance.
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| 3. |
- Ungerbäck, Jonas, et al.
(författare)
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Pioneering, chromatin remodeling, and epigenetic constraint in early T-cell gene regulation by SPIT (PU.1)
- 2018
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Ingår i: Genome Research. - : COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT. - 1088-9051 .- 1549-5469. ; 28:10, s. 1508-1519
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Tidskriftsartikel (refereegranskat)abstract
- SPI1 (also known as PU.1) is a dominant but transient regulator in early T-cell precursors and a potent transcriptional controller of developmentally important pro-T-cell genes. Before T-lineage commitment, open chromatin is frequently occupied by PU.1, and many PU.1 sites lose accessibility when PU.1 is later down-regulated. Pioneering activity of PU.1 was tested in this developmentally dynamic context by quantitating the relationships between PU.1 occupancy and site quality and accessibility as PU.1 levels naturally declined in pro-T-cell development and by using stage-specific gain- and loss-offunction perturbations to relate binding to effects on target genes. PU.1 could bind closed genomic sites, but rapidly opened many of them, despite the absence of its frequent collaborator, CEBPA. RUNX motifs and RUNX1 binding were often linked to PU.1 at open sites, but highly expressed PU.1 could bind its sites without RUNX1 The dynamic properties of PU.1 engagements implied that PU.1 binding affinity and concentration determine its occupancy choices, but with quantitative trade-offs for occupancy between site sequence quality and stage-dependent site accessibility in chromatin. At nonpromoter sites, PU.1 binding criteria were more stringent than at promoters, and PU.1 was also much more effective as a transcriptional regulator at non promoter sites where local chromatin accessibility depended on the presence of PU.1. Notably, closed chromatin presented a qualitative barrier to occupancy by the PU.1 DNA-binding domain alone. Thus, effective pioneering at closed chromatin sites also depends on requirements beyond site recognition, served by non-DNA-binding domains of PU.1.
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