Ets proteins: new factors that regulate immunoglobulin heavy-chain gene expression

1993 ◽  
Vol 13 (11) ◽  
pp. 7163-7169
Author(s):  
R R Rivera ◽  
M H Stuiver ◽  
R Steenbergen ◽  
C Murre

We used a DNA-protein interaction screening method to isolate a cDNA, Erg-3, whose product binds to a site, designated pi, present in the immunoglobulin (Ig) heavy-chain gene enhancer. Erg-3 is an alternatively spliced product of the erg gene and contains an Ets DNA-binding domain. Fli-1 and PU.1, related Ets proteins, also bind to the same site. In addition, PU.1 binds to a second site, designated microB, in the Ig heavy-chain enhancer. We demonstrate that the pi binding site is crucial for Ig heavy-chain gene enhancer function. In addition, we show that Erg-3 and Fli.1, but not PU.1, can activate a reporter construct containing a multimer of protein-binding sites, synergistically with helix-loop-helix protein E12. We discuss how combinatorial interactions between members of the helix-loop-helix and Ets families may account for the tissue specificity of these proteins.

1993 ◽  
Vol 13 (11) ◽  
pp. 7163-7169 ◽  
Author(s):  
R R Rivera ◽  
M H Stuiver ◽  
R Steenbergen ◽  
C Murre

We used a DNA-protein interaction screening method to isolate a cDNA, Erg-3, whose product binds to a site, designated pi, present in the immunoglobulin (Ig) heavy-chain gene enhancer. Erg-3 is an alternatively spliced product of the erg gene and contains an Ets DNA-binding domain. Fli-1 and PU.1, related Ets proteins, also bind to the same site. In addition, PU.1 binds to a second site, designated microB, in the Ig heavy-chain enhancer. We demonstrate that the pi binding site is crucial for Ig heavy-chain gene enhancer function. In addition, we show that Erg-3 and Fli.1, but not PU.1, can activate a reporter construct containing a multimer of protein-binding sites, synergistically with helix-loop-helix protein E12. We discuss how combinatorial interactions between members of the helix-loop-helix and Ets families may account for the tissue specificity of these proteins.


1998 ◽  
Vol 18 (3) ◽  
pp. 1477-1488 ◽  
Author(s):  
Wei Dang ◽  
Xiao-hong Sun ◽  
Ranjan Sen

ABSTRACT The μE motifs of the immunoglobulin μ heavy-chain gene enhancer bind ubiquitously expressed proteins of the basic helix-loop-helix (bHLH) family. These elements work together with other, more tissue-restricted elements to produce B-cell-specific enhancer activity by presently undefined combinatorial mechanisms. We found that μE2 contributed to transcription activation in B cells only when the μE3 site was intact, providing the first evidence for functional interactions between bHLH proteins. In vitro assays showed that bHLH zipper proteins binding to μE3 enhanced Ets-1 binding to μA. One of the consequences of this protein-protein interaction was to facilitate binding of a second bHLH protein, E47, to the μE2 site, thereby generating a three-protein–DNA complex. Furthermore, transcriptional synergy between bHLH and bHLH zipper factors also required an intermediate ETS protein, which may bridge the transcription activation domains of the bHLH factors. Our observations define an unusual form of cooperation between bHLH and ETS proteins and suggest mechanisms by which tissue-restricted and ubiquitous factors combine to generate tissue-specific enhancer activity.


1987 ◽  
Vol 15 (7) ◽  
pp. 2851-2869 ◽  
Author(s):  
Hiroaki Maeda ◽  
Kazuo Araki ◽  
Daisuke Kitamura ◽  
Jiyang Wang ◽  
Takeshi Watanabe

Science ◽  
1993 ◽  
Vol 261 (5117) ◽  
pp. 82-86 ◽  
Author(s):  
B Nelsen ◽  
G Tian ◽  
B Erman ◽  
J Gregoire ◽  
R Maki ◽  
...  

1990 ◽  
Vol 10 (6) ◽  
pp. 3145-3154 ◽  
Author(s):  
B Nelsen ◽  
T Kadesch ◽  
R Sen

The B-lymphocyte-specific activity of the immunoglobulin mu heavy-chain gene enhancer has been attributed to the octamer motif (ATTTGCAT) present within the enhancer that binds a B-cell-specific factor designated NF-A2/OTF-2. However, significant residual enhancer activity even after deletion of this element has suggested the presence of a second critical functional determinant. We have used deletion and mutational analyses to define an element, microB (TTTGGGGAA), that is essential for B-cell-specific enhancer activity in S194 myeloma cells in the absence of the octamer. Transfection analysis in a panel of lymphoid cell lines suggests that the presence of either microB or octamer leads to considerable enhancer activity in cell lines representing later stages of B-cell differentiation, whereas both elements are needed for function in cell lines representing earlier stages. Furthermore, in contrast to the results in pre-B-cell lines, both microB and octamer elements function independently in certain T-cell lines in which the mu enhancer is active.


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