scholarly journals Regulation of the T-cell receptor delta enhancer by functional cooperation between c-Myb and core-binding factors.

1994 ◽  
Vol 14 (1) ◽  
pp. 473-483 ◽  
Author(s):  
C Hernandez-Munain ◽  
M S Krangel

A T-cell-specific transcriptional enhancer lies within the J delta 3-C delta intron of the human T-cell receptor (TCR) delta gene. The 30-bp minimal enhancer element denoted delta E3 carries a core sequence (TGTGGTTT) that binds a T-cell-specific factor, and that is necessary but not sufficient for transcriptional activation. Here we demonstrate that the transcription factor c-Myb regulates TCR delta enhancer activity through a binding site in delta E3 that is adjacent to the core site. Both v-Myb and c-Myb bind specifically to delta E3. The Myb site is necessary for enhancer activity, because a mutation that eliminates Myb binding abolishes transcriptional activation by the delta E3 element and by the 370-bp TCR delta enhancer. Transfection of cells with a c-Myb expression construct upregulates delta E3 enhancer activity, whereas treatment of cells with an antisense c-myb oligonucleotide inhibits delta E3 enhancer activity. Since intact Myb and core sites are both required for delta E3 function, our data argue that c-Myb and core binding factors must cooperate to mediate transcriptional activation through delta E3. Efficient cooperation depends on the relative positioning of the Myb and core sites, since only one of two overlapping Myb sites within delta E3 is functional and alterations of the distance between this site and the core site disrupt enhancer activity. Cooperative regulation by c-Myb and core-binding factors is likely to play an important role in the control of gene expression during T-cell development.

1994 ◽  
Vol 14 (1) ◽  
pp. 473-483
Author(s):  
C Hernandez-Munain ◽  
M S Krangel

A T-cell-specific transcriptional enhancer lies within the J delta 3-C delta intron of the human T-cell receptor (TCR) delta gene. The 30-bp minimal enhancer element denoted delta E3 carries a core sequence (TGTGGTTT) that binds a T-cell-specific factor, and that is necessary but not sufficient for transcriptional activation. Here we demonstrate that the transcription factor c-Myb regulates TCR delta enhancer activity through a binding site in delta E3 that is adjacent to the core site. Both v-Myb and c-Myb bind specifically to delta E3. The Myb site is necessary for enhancer activity, because a mutation that eliminates Myb binding abolishes transcriptional activation by the delta E3 element and by the 370-bp TCR delta enhancer. Transfection of cells with a c-Myb expression construct upregulates delta E3 enhancer activity, whereas treatment of cells with an antisense c-myb oligonucleotide inhibits delta E3 enhancer activity. Since intact Myb and core sites are both required for delta E3 function, our data argue that c-Myb and core binding factors must cooperate to mediate transcriptional activation through delta E3. Efficient cooperation depends on the relative positioning of the Myb and core sites, since only one of two overlapping Myb sites within delta E3 is functional and alterations of the distance between this site and the core site disrupt enhancer activity. Cooperative regulation by c-Myb and core-binding factors is likely to play an important role in the control of gene expression during T-cell development.


1991 ◽  
Vol 11 (11) ◽  
pp. 5671-5680 ◽  
Author(s):  
J M Redondo ◽  
J L Pfohl ◽  
M S Krangel

A T-cell-specific transcriptional enhancer was previously identified within the J delta 3-C delta intron of the human T-cell receptor (TCR) delta gene, and seven distinct binding sites for nuclear factors (delta E1 to delta E7) were defined by DNase I footprinting. In this study, we conducted a detailed functional analysis of the various cis-acting DNA sequence elements of the enhancer and show that a 60-bp fragment encompassing delta E3 and delta E4 displays potent enhancer activity, as judged by its ability to activate transcription from the V delta 1 promoter. We show that the interaction of nuclear factors with the delta E3 site is essential for enhancer activity. This element displays significant activity in the absence of additional segments of the enhancer. Further, methylation interference and in vitro mutagenesis identify a site within delta E3 that mediates the binding of two nuclear factors (NF-delta E3A and NF-delta E3C) and that is required for significant transcriptional activation by the enhancer. NF-delta E3C is ubiquitous and may be identical to a previously characterized microE3-binding factor. NF-delta E3A is preferentially expressed in T lymphocytes, and we suggest that this factor may play the dominant role in transcriptional activation through the delta E3 site. This factor interacts with the sequence TGTGGTTT, a motif that is also found within the enhancers of additional TCR and CD3 genes. Nuclear factor binding to delta E4 is also analyzed. One of three specific complexes formed with a delta E4 probe appears to be T-cell specific.


1993 ◽  
Vol 13 (6) ◽  
pp. 3324-3339
Author(s):  
S Wang ◽  
Q Wang ◽  
B E Crute ◽  
I N Melnikova ◽  
S R Keller ◽  
...  

Moloney murine leukemia virus causes thymic leukemias when injected into newborn mice. A major determinant of the thymic disease specificity of Moloney virus genetically maps to the conserved viral core motif in the Moloney virus enhancer. Point mutations introduced into the core site significantly shifted the disease specificity of the Moloney virus from thymic leukemia to erythroid leukemia (N.A. Speck, B. Renjifo, E. Golemis, T.N. Fredrickson, J.W. Hartley, and N. Hopkins, Genes Dev. 4:233-242, 1990). We previously reported the purification of core-binding factors (CBF) from calf thymus nuclei (S. Wang and N.A. Speck, Mol. Cell. Biol. 12:89-102, 1992). CBF binds to core sites in murine leukemia virus and T-cell receptor enhancers. Affinity-purified CBF contains multiple polypeptides. In this study, we sequenced five tryptic peptides from two of the bovine CBF proteins and isolated three cDNA clones from a mouse thymus cDNA library encoding three of the tryptic peptides from the bovine proteins. The cDNA clones, which we call CBF beta p22.0, CBF beta p21.5, and CBF beta p17.6, encode three highly related but distinct proteins with deduced molecular sizes of 22.0, 21.5, and 17.6 kDa that appear to be translated from multiply spliced mRNAs transcribed from the same gene. CBF beta p22.0, CBF beta p21.5, and CBF beta p17.6 do not by themselves bind the core site. However, CBF beta p22.0 and CBF beta p21.5 form a complex with DNA-binding CBF alpha subunits and as a result decrease the rate of dissociation of the CBF protein-DNA complex. Association of the CBF beta subunits does not extend the phosphate contacts in the binding site. We propose that CBF beta is a non-DNA-binding subunit of CBF and does not contact DNA directly.


1993 ◽  
Vol 13 (6) ◽  
pp. 3324-3339 ◽  
Author(s):  
S Wang ◽  
Q Wang ◽  
B E Crute ◽  
I N Melnikova ◽  
S R Keller ◽  
...  

Moloney murine leukemia virus causes thymic leukemias when injected into newborn mice. A major determinant of the thymic disease specificity of Moloney virus genetically maps to the conserved viral core motif in the Moloney virus enhancer. Point mutations introduced into the core site significantly shifted the disease specificity of the Moloney virus from thymic leukemia to erythroid leukemia (N.A. Speck, B. Renjifo, E. Golemis, T.N. Fredrickson, J.W. Hartley, and N. Hopkins, Genes Dev. 4:233-242, 1990). We previously reported the purification of core-binding factors (CBF) from calf thymus nuclei (S. Wang and N.A. Speck, Mol. Cell. Biol. 12:89-102, 1992). CBF binds to core sites in murine leukemia virus and T-cell receptor enhancers. Affinity-purified CBF contains multiple polypeptides. In this study, we sequenced five tryptic peptides from two of the bovine CBF proteins and isolated three cDNA clones from a mouse thymus cDNA library encoding three of the tryptic peptides from the bovine proteins. The cDNA clones, which we call CBF beta p22.0, CBF beta p21.5, and CBF beta p17.6, encode three highly related but distinct proteins with deduced molecular sizes of 22.0, 21.5, and 17.6 kDa that appear to be translated from multiply spliced mRNAs transcribed from the same gene. CBF beta p22.0, CBF beta p21.5, and CBF beta p17.6 do not by themselves bind the core site. However, CBF beta p22.0 and CBF beta p21.5 form a complex with DNA-binding CBF alpha subunits and as a result decrease the rate of dissociation of the CBF protein-DNA complex. Association of the CBF beta subunits does not extend the phosphate contacts in the binding site. We propose that CBF beta is a non-DNA-binding subunit of CBF and does not contact DNA directly.


1991 ◽  
Vol 11 (11) ◽  
pp. 5671-5680
Author(s):  
J M Redondo ◽  
J L Pfohl ◽  
M S Krangel

A T-cell-specific transcriptional enhancer was previously identified within the J delta 3-C delta intron of the human T-cell receptor (TCR) delta gene, and seven distinct binding sites for nuclear factors (delta E1 to delta E7) were defined by DNase I footprinting. In this study, we conducted a detailed functional analysis of the various cis-acting DNA sequence elements of the enhancer and show that a 60-bp fragment encompassing delta E3 and delta E4 displays potent enhancer activity, as judged by its ability to activate transcription from the V delta 1 promoter. We show that the interaction of nuclear factors with the delta E3 site is essential for enhancer activity. This element displays significant activity in the absence of additional segments of the enhancer. Further, methylation interference and in vitro mutagenesis identify a site within delta E3 that mediates the binding of two nuclear factors (NF-delta E3A and NF-delta E3C) and that is required for significant transcriptional activation by the enhancer. NF-delta E3C is ubiquitous and may be identical to a previously characterized microE3-binding factor. NF-delta E3A is preferentially expressed in T lymphocytes, and we suggest that this factor may play the dominant role in transcriptional activation through the delta E3 site. This factor interacts with the sequence TGTGGTTT, a motif that is also found within the enhancers of additional TCR and CD3 genes. Nuclear factor binding to delta E4 is also analyzed. One of three specific complexes formed with a delta E4 probe appears to be T-cell specific.


2016 ◽  
Vol 291 (16) ◽  
pp. 8440-8452 ◽  
Author(s):  
Xiaohong Liu ◽  
Corbett T. Berry ◽  
Gordon Ruthel ◽  
Jonathan J. Madara ◽  
Katelyn MacGillivray ◽  
...  

1990 ◽  
Vol 10 (10) ◽  
pp. 5486-5495
Author(s):  
L R Gottschalk ◽  
J M Leiden

A transcriptional enhancer has been mapped to a region 5.5 kilobases 3' of the C beta 2 gene in the human T-cell receptor (TCR) beta-chain locus. Transient transfections allowed localization of enhancer activity to a 480-base-pair HincII-XbaI restriction enzyme fragment. The TCR beta enhancer was active on both the minimal simian virus 40 promoter and a TCR beta variable gene promoter in both TCR alpha/beta + and TCR gamma/delta + T cells. It displayed significantly less activity in Epstein-Barr virus-transformed B cells and K562 chronic myelogenous leukemia cells and no activity in HeLa fibroblasts. DNA sequence analysis revealed that the enhancer contains a consensus immunoglobulin kappa E2 motif, as well as an AP-1-binding site and a cyclic AMP response element. DNase I footprint analyses using Jurkat T-cell nuclear extracts allowed the identification of five nuclear protein-binding sites, T beta 1 to T beta 5, within the enhancer element. Deletion and in vitro mutagenesis studies demonstrated that the T beta 2- and T beta 3- and T beta 4-binding sites are each required for full transcriptional enhancer activity. In contrast, deletion of the T beta 1- and T beta 5-binding sites had essentially no effect on enhancer function. Electrophoretic mobility shift assays demonstrated that TCR alpha/beta + and TCR gamma/delta + T cells expressed T beta 2-, T beta 3-, and T beta 4-binding activities. In contrast, non-T-cell lines, in which the enhancer was inactive, each lacked expression of at least one of these binding activities. TCR alpha and beta gene expression may be regulated by a common set of T-cell nuclear proteins in that the T beta 2 element binding a set of cyclic AMP response element-binding proteins that are also bound by the T alpha 1 element of the human TCR alpha enhancer and the decamer element present in a large number of human and murine TCR beta promoters. Similarly, the T beta 5 TCR beta-enhancer element and the T alpha 2 TCR alpha-enhancer element bind at least one common T-cell nuclear protein. Taken together, these results suggest that TCR beta gene expression is regulated by the interaction of multiple T cell nuclear proteins with a transcriptional enhancer element located 3' of the C beta 2 gene and that some of these proteins may be involved in the coordinate regulation of TCR alpha and beta gene expression.


1990 ◽  
Vol 10 (10) ◽  
pp. 5027-5035
Author(s):  
J Takeda ◽  
A Cheng ◽  
F Mauxion ◽  
C A Nelson ◽  
R D Newberry ◽  
...  

The minimal T-cell receptor (TCR) beta-chain (TCR beta) enhancer has been identified by transfection into lymphoid cells. The minimal enhancer was active in T cells and in some B-lineage cells. When a larger fragment containing the minimal enhancer was used, its activity was apparent only in T cells. Studies with phytohemagglutinin and 4 beta-phorbol-12,13-dibutyrate revealed that the enhancer activity was increased by these agents. By a combination of DNase I footprinting, gel mobility shift assay, and methylation interference analysis, seven different motifs were identified within the minimal enhancer. Furthermore, competition experiments showed that some of these elements bound identical or similar factors that are known to bind to the TCR V beta promoter decamer or to the immunoglobulin enhancer kappa E2 or muEBP-E motif. These shared motifs may be important in the differential gene activity among the different lymphoid subsets.


1992 ◽  
Vol 12 (11) ◽  
pp. 4817-4823 ◽  
Author(s):  
J M Redondo ◽  
J L Pfohl ◽  
C Hernandez-Munain ◽  
S Wang ◽  
N A Speck ◽  
...  

We have previously shown that the delta E3 site is an essential element for transcriptional activation by the human T-cell receptor (TCR) delta enhancer and identified two factors, NF-delta E3A and NF-delta E3C, that bound to overlapping core (TGTGGTTT) and E-box motifs within delta E3. In this study, we show that protein binding to the core motif is necessary but not sufficient for transcriptional activation by the delta E3 element. In contrast, protein binding to the E-box motif does not contribute significantly to enhancer activity. A similar core motif present within the enhancers of T-cell-tropic murine retroviruses has been shown to contribute to transcriptional activity of the viral long terminal repeat in T lymphocytes and to viral T-cell tropism. We therefore determined the relationship between the nuclear factors that bind to the TCR delta and Moloney murine leukemia virus core motifs. On the basis of electrophoretic mobility shift binding and competition studies, biochemical analysis of affinity-labeled DNA-binding proteins, and the binding of a purified core binding factor, the proteins that bound to the TCR delta core site were indistinguishable from those that bound to the murine leukemia virus core site. These data argue that DNA-binding proteins that interact with the core site of murine leukemia virus long terminal repeats and contribute to viral T-cell tropism also play an essential role in the T-cell-specific expression of cellular genes.


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