Germline transcription from T-cell receptor Vβ gene is uncoupled from allelic exclusion

Jia, Jingquan; Kondo, Motonari; Zhuang, Yuan

doi:10.1038/sj.emboj.7601671

Cited by 24 publications

(30 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Loss of accessibility and locus decontraction both contribute to the maintenance of allelic exclusion, because V β and DJ β segments engineered to be accessible and proximal are capable of recombination in DP thymocytes (9, 10). However, because both Tcrb alleles appear to be accessible (11,12) and contracted (8) before rearrangement in DN thymocytes, the mechanism by which the locus is biased to undergo asynchronous V β -to-DJ β recombination in DN thymocytes is unknown.It has been suggested that subnuclear positioning can regulate V(D)J recombination at TCR and BCR loci. For example, association with pericentromeric heterochromatin (PCH) has been linked to the process of allelic exclusion.…”

mentioning

confidence: 99%

Peripheral subnuclear positioning suppresses Tcrb recombination and segregates Tcrb alleles from RAG2

Chan¹,

Teng²,

Corbett³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Allelic exclusion requires that the two alleles at antigen-receptor loci attempt to recombine variable (V), diversity (D), and joining (J) gene segments [V(D)J recombination] asynchronously in nuclei of developing lymphocytes. It previously was shown that T-cell receptor β (Tcrb) alleles frequently and stochastically associate with the nuclear lamina and pericentromeric heterochromatin in CD4 − CD8− thymocytes. Moreover, rearranged alleles were underrepresented at these locations. Here we used 3D immunofluorescence in situ hybridization to identify recently rearranged Tcrb alleles based on the accumulation of the DNA-repair protein 53BP1. We found that Tcrb alleles recombine asynchronously in double-negative thymocytes and that V(D)J recombination is suppressed on peripheral as compared with central Tcrb alleles. Moreover, the recombination events that did take place at the nuclear periphery preferentially occurred on Tcrb alleles that were partially dissociated from the nuclear lamina. To understand better the mechanism by which V(D)J recombination is suppressed at the nuclear periphery, we evaluated the subnuclear distribution of recombination-activating gene 2 (RAG2) protein. We found that RAG2 abundance was reduced at the nuclear periphery. Moreover, RAG2 was distributed differently from RNA polymerase II and histone H3K4 trimethylation. Our data suggest that the nuclear periphery suppresses V(D)J recombination, at least in part, by segregating Tcrb alleles from RAG proteins.T-cell development | thymus A ntigen receptor variable (V), diversity (D), and joining (J) gene segments are assembled by V(D)J recombination in immature T and B lymphocytes to generate diverse repertoires of T-cell receptors (TCRs) and B-cell receptors (BCRs), respectively (1). V(D)J recombination is initiated by the recombination-activating gene (RAG) 1 and 2 proteins, which bind to and induce double-strand breaks (DSBs) at recombination signal sequences that flank V, D, and J segments. V(D)J recombination at antigen-receptor loci is regulated according to cell lineage and developmental stage (2). In addition, at some loci V (D)J recombination is regulated to enforce allelic exclusion, so that a complete antigen-receptor protein is produced by only one allele (3, 4). However, the mechanisms that establish allelic exclusion are poorly understood.Among TCR loci, only the T-cell receptor β (Tcrb) locus is allelically excluded (5). Tcrb recombination occurs in CD4 − CD8 − double-negative (DN) thymocytes and is ordered, beginning with D β -J β rearrangement, which can occur on both alleles. Allelic exclusion then is initiated by V β -to-DJ β recombination, which is thought to occur asynchronously, i.e., on one allele at a time. This asynchrony allows thymocytes time to test each allele for the creation of an ORF. TCRβ proteins are sensed by their assembly with pre-Tα and CD3 chains to create a pre-TCR signaling complex; pre-TCR signals then suppress further Tcrb recombination and promote thymocyte proliferation and differentiation to the CD...

show abstract

mentioning

confidence: 99%

Peripheral subnuclear positioning suppresses Tcrb recombination and segregates Tcrb alleles from RAG2

Chan¹,

Teng²,

Corbett³

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…However, in these cases, the model no longer accurately matched the reported figures, with best-predicted scores (17,15,4) [instead of (16,13,7); pTa 2/2 T cells] and (19,21,5) [instead of (18,19,8); SPL-76 2/2 T cells] (minimized distances .0.25, of ∼29 in both cases). We can think of two reasons to account for this unique setback.…”

Section: Fitting Statistics From Preselected Dn Thymocytesmentioning

confidence: 78%

“…For example, the extended value of t VDJ may relate to an epigenetic-based recombination hindrance that would bestow on the two alleles differential capabilities for Vb-to-DJb assembly. In this context, it is notable that the unrearranged Vb domains/alleles were found to be overmethylated and to frequently associate with repressive compartments in DN nuclei, even though the Vb region is biallelically expressed at this stage (12,18,63). Of note, as long as the key issue rests on a mechanism capable of generating a time lag in the assembly of homologous alleles, a two-step recombination process should mechanically help to this outcome, not only in mathematical simulation but also in reality at the given locus.…”

Section: Discussionmentioning

confidence: 99%

“…However, recent investigations questioning the validity of the GFP system in supplying evidence for probabilistic gene expression at Igk alleles (59,60) cast doubt on these numerical data. In fact, as with the Vb locus in pro-T cells (18), GL Igk transcription seems to occur biallelically in single pre-B cells (59)(60)(61). Separately, using immunofluorescence in situ hybridization, TCRb alleles were found to associate at a high frequency and presumably stochastically with repressive nuclear compartments (i.e., the pericentric heterochromatin and nuclear lamina), such that only 5% of nuclei showed two alleles free of both compartments against ∼60% still showing potentially repressive dual interactions (12).…”

Section: Discussionmentioning

confidence: 99%

“…Principally, successive D-to-J and V-to-DJ rearrangements at TCRb alleles of individual T cells and ensuing feedback inhibition are seen throughout as independent, possibly concurrent and mostly not stringently simultaneous biochemical transactions, with fluctuating modes of initiation and duration. Indeed, evidence that developing T cells exhibit uniformed, biallelic transcription of a Vb gene before recombination (18) makes allele autonomy in the conduct of TCRb rearrangements a plausible hypothesis. Besides, the variety of rearranging sequences (19) and multiplicity of molecular factors/mechanisms involved in TCRb gene recombination and feedback signaling (16,20) strongly favor a widespread noise in, and randomness of, all these events.…”

mentioning

confidence: 99%

See 2 more Smart Citations

TCRβ Allelic Exclusion in Dynamical Models of V(D)J Recombination Based on Allele Independence

Farcot

Bonnet

Jaeger

et al. 2010

The Journal of Immunology

View full text Add to dashboard Cite

show abstract

E proteins are required to activate germline transcription of the TCR Vβ8.2 gene

2008

Self Cite

View full text Add to dashboard Cite

Each TCR Vb gene is regulated by an individual Vb promoter, which becomes active prior to V(D) J recombination and drives germline transcription. It has been shown that Vb gene locus activation and recombination are dependent on the Vb promoter. However, transcription factors that regulate Vb germline transcription remain largely undefined. A major challenge in studying Vb gene germline transcription is the quantitative assessment of relatively low-level transcripts in T-cell progenitors. Here we used the established Vb8.2 CD2 knock-in mouse model to assess functions of E-protein transcription factors in Vb8.2 germline transcription. We show that E proteins are required for the activation but not the maintenance of the Vb8.2 germline transcription during thymocyte development. The activation of Vb8.2 germline transcription depends more on the E proteins encoded by the E2A gene than by the HEB gene. We further show that IL-7 receptor (IL-7R)-mediated signals are essential for Vb8.2 germline transcription. We provide evidence that IL-7R expression is only partially controlled by E2A, suggesting a role for E2A in driving Vb8.2 germline transcription independent of IL-7R activation. [21]. HEB KO mice display a developmental arrest at the CD8 immature SP stage, a transitional stage between the DN and DP stages of thymocyte development [22]. E2A/HEB heterodimers are the major functional player during T-cell development. A point mutation in the HEB basic region that abolishes HEB DNA-binding activity disrupts the function of both E2A and HEB, resulting in a block in T-cell development at the DN stage. This is the most severe and complete block in T-cell development among the established individual E-protein gene mutations [23]. E2A and HEB have been shown to induce TCRg and TCRd gene rearrangement and germline transcription when ectopically expressed in a nonlymphoid cell line [24]. E2A has also been reported to inhibit germline transcription and rearrangement of fetal Vg and Vd genes while it activates postnatal Vg and Vd genes in adult mice [25]. However, the role of E2A and HEB in regulating Vb gene germline transcription during thymocyte development remains largely undefined.We previously generated a TCR Vb8.2 CD2 knock-in allele in which a tail-less human CD2 cDNA driven by an internal ribosome entry site was placed 1.5 kbp upstream of the putative poly(A) site and 104 bp downstream of Vb8.2 recombination signal sequence. Therefore, the hCD2 marker will be expressed exclusively from germline transcription and will be deleted after recombination involving Vb8.2 or any

show abstract

Germline transcription from T-cell receptor Vβ gene is uncoupled from allelic exclusion

Cited by 24 publications

References 44 publications

Peripheral subnuclear positioning suppresses Tcrb recombination and segregates Tcrb alleles from RAG2

Peripheral subnuclear positioning suppresses Tcrb recombination and segregates Tcrb alleles from RAG2

TCRβ Allelic Exclusion in Dynamical Models of V(D)J Recombination Based on Allele Independence

E proteins are required to activate germline transcription of the TCR Vβ8.2 gene

Contact Info

Product

Resources

About