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Lineage-specific compaction of Tcrb requires a chromatin barrier to protect the function of a long-range tethering element.

Majumder K, Koues OI, Chan EA, Kyle KE, Horowitz JE, Yang-Iott K, Bassing CH, Taniuchi I, Krangel MS, Oltz EM - J. Exp. Med. (2014)

Bottom Line: The second element is a chromatin barrier that protects the tether from hyperactive RC chromatin.When the second element is removed, active RC chromatin spreads upstream, forcing the tether to serve as a new barrier.Acquisition of barrier function by the CTCF element disrupts contacts between distal Vβ gene segments and significantly alters Tcrb repertoires.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110.

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Long-range Trbv looping to 5′PC requires an RC barrier element. (A) Expression of Prss2 transcripts were measured by RT-qPCR relative to Actb in DN thymocytes (WT, ΔPDβ1, ΔminPDβ1, and mEβ mice) and in spleen from C57BL/6 mice (positive control). (B–D) ChIP-qPCR assays were performed in DN thymocytes from RAG1−/− mice in the indicated Tcrb genotypes. Shown are levels of the H3K4me3 modification at the indicated promoters (B), as well as levels for active histone marks H3ac (C, top) and H3K4me2 (C, bottom) and repressive histone marks H3K9me2 (D, top) and H3K27me3 (D, bottom) at the indicated sites upstream or within the RC. All data are represented as means (±SEM) of at least two independent experiments. Thymocytes were pooled from four to eight mice for each experiment. Significant differences between only the WT and ΔPDβ1 genotypes are denoted as *, P ≤ 0.05 (Student’s t test).
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fig7: Long-range Trbv looping to 5′PC requires an RC barrier element. (A) Expression of Prss2 transcripts were measured by RT-qPCR relative to Actb in DN thymocytes (WT, ΔPDβ1, ΔminPDβ1, and mEβ mice) and in spleen from C57BL/6 mice (positive control). (B–D) ChIP-qPCR assays were performed in DN thymocytes from RAG1−/− mice in the indicated Tcrb genotypes. Shown are levels of the H3K4me3 modification at the indicated promoters (B), as well as levels for active histone marks H3ac (C, top) and H3K4me2 (C, bottom) and repressive histone marks H3K9me2 (D, top) and H3K27me3 (D, bottom) at the indicated sites upstream or within the RC. All data are represented as means (±SEM) of at least two independent experiments. Thymocytes were pooled from four to eight mice for each experiment. Significant differences between only the WT and ΔPDβ1 genotypes are denoted as *, P ≤ 0.05 (Student’s t test).

Mentions: The region of interest has several distinguishing characteristics, including a repetitive tract at its 5′ end and a pair of low-intensity CTCF/RAD21-binding sites (Fig. 6 A, bottom). These features are reminiscent of insulators that form boundaries between active and repressive chromatin domains (Wendt et al., 2008). In keeping with this possibility, a gene situated upstream of the putative chromatin barrier, Prss2, is transcriptionally active in ΔPDβ1 thymocytes but is completely silent in the context of WT, ΔminPDβ1, or mEβ alleles (Fig. 7 A). Prss2 activation in ΔPDβ1 thymocytes is mirrored by an acquisition of H3K4me3 at its promoter region (Fig. 7 B).


Lineage-specific compaction of Tcrb requires a chromatin barrier to protect the function of a long-range tethering element.

Majumder K, Koues OI, Chan EA, Kyle KE, Horowitz JE, Yang-Iott K, Bassing CH, Taniuchi I, Krangel MS, Oltz EM - J. Exp. Med. (2014)

Long-range Trbv looping to 5′PC requires an RC barrier element. (A) Expression of Prss2 transcripts were measured by RT-qPCR relative to Actb in DN thymocytes (WT, ΔPDβ1, ΔminPDβ1, and mEβ mice) and in spleen from C57BL/6 mice (positive control). (B–D) ChIP-qPCR assays were performed in DN thymocytes from RAG1−/− mice in the indicated Tcrb genotypes. Shown are levels of the H3K4me3 modification at the indicated promoters (B), as well as levels for active histone marks H3ac (C, top) and H3K4me2 (C, bottom) and repressive histone marks H3K9me2 (D, top) and H3K27me3 (D, bottom) at the indicated sites upstream or within the RC. All data are represented as means (±SEM) of at least two independent experiments. Thymocytes were pooled from four to eight mice for each experiment. Significant differences between only the WT and ΔPDβ1 genotypes are denoted as *, P ≤ 0.05 (Student’s t test).
© Copyright Policy - openaccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4291525&req=5

fig7: Long-range Trbv looping to 5′PC requires an RC barrier element. (A) Expression of Prss2 transcripts were measured by RT-qPCR relative to Actb in DN thymocytes (WT, ΔPDβ1, ΔminPDβ1, and mEβ mice) and in spleen from C57BL/6 mice (positive control). (B–D) ChIP-qPCR assays were performed in DN thymocytes from RAG1−/− mice in the indicated Tcrb genotypes. Shown are levels of the H3K4me3 modification at the indicated promoters (B), as well as levels for active histone marks H3ac (C, top) and H3K4me2 (C, bottom) and repressive histone marks H3K9me2 (D, top) and H3K27me3 (D, bottom) at the indicated sites upstream or within the RC. All data are represented as means (±SEM) of at least two independent experiments. Thymocytes were pooled from four to eight mice for each experiment. Significant differences between only the WT and ΔPDβ1 genotypes are denoted as *, P ≤ 0.05 (Student’s t test).
Mentions: The region of interest has several distinguishing characteristics, including a repetitive tract at its 5′ end and a pair of low-intensity CTCF/RAD21-binding sites (Fig. 6 A, bottom). These features are reminiscent of insulators that form boundaries between active and repressive chromatin domains (Wendt et al., 2008). In keeping with this possibility, a gene situated upstream of the putative chromatin barrier, Prss2, is transcriptionally active in ΔPDβ1 thymocytes but is completely silent in the context of WT, ΔminPDβ1, or mEβ alleles (Fig. 7 A). Prss2 activation in ΔPDβ1 thymocytes is mirrored by an acquisition of H3K4me3 at its promoter region (Fig. 7 B).

Bottom Line: The second element is a chromatin barrier that protects the tether from hyperactive RC chromatin.When the second element is removed, active RC chromatin spreads upstream, forcing the tether to serve as a new barrier.Acquisition of barrier function by the CTCF element disrupts contacts between distal Vβ gene segments and significantly alters Tcrb repertoires.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110.

Show MeSH
Related in: MedlinePlus