Abstract
The Brg1/Brm-associated factor (BAF) chromatin remodeling complex directly binds the CD4 silencer and is essential for CD4 repressigg during T-cell development, because deletion of the ATPase subunit Brg1 or a dominant negative mutant of BAF57 each impairs CD4 repression in early thymocytes. Paradoxically, BAF57 is dispensable for remodeling nucleosomes in vitro or for binding of the BAF complex to the CD4 silencer in vivo. Thus, it is unclear whether BAF57-dependent CD4 repression involves chromatin remodeling and, if so, how the remodeling translates into CD4 repression. Here we show that nucleosomes at the CD4 silencer occupy multiple translational frames. BAF57 dominant negative mutant does not alter these frames, but reduces the accessibility of the entire silencer without affecting the flanking regions, concomitant with localized accumulation of linker histone H1 and eviction of Runx1, a key repressor of CD4 transcription that directly binds the CD4 silencer. Our data indicate that precise nucleosome positioning is not critical for the CD4 silencer function and that BAF57 participates in remodeling H1-containing chromatin at the CD4 silencer, which enables Runx1 to access the silencer and repress CD4. In addition to BAF57, multiple other subunits in the BAF complex are also dispensable for chromatin remodelling in vitro. Our data suggest that these subunits could also help remodel chromatin at a step after the recruitment of the BAF complex to target genes.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 580-588 |
| Number of pages | 9 |
| Journal | European Journal of Immunology |
| Volume | 39 |
| Issue number | 2 |
| DOIs | |
| State | Published - 2009 |
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Keywords
- BAF27
- CD4
- Chromatin
ASJC Scopus subject areas
- Immunology
- Immunology and Allergy
Cite this
Molecular basis of CD4 repression by the Swi/Snf-like BAF chromatin remodeling complex. / Wan, Mimi; Zhang, Jianmin; Lai, Dazhi; Jani, Anant; Prestone-Hurlburt, Paula; Zhao, Lulu; Ramachandran, Aruna; Schnitzler, Gavin R.; Chi, Tian.
In: European Journal of Immunology, Vol. 39, No. 2, 2009, p. 580-588.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Molecular basis of CD4 repression by the Swi/Snf-like BAF chromatin remodeling complex
AU - Wan, Mimi
AU - Zhang, Jianmin
AU - Lai, Dazhi
AU - Jani, Anant
AU - Prestone-Hurlburt, Paula
AU - Zhao, Lulu
AU - Ramachandran, Aruna
AU - Schnitzler, Gavin R.
AU - Chi, Tian
PY - 2009
Y1 - 2009
N2 - The Brg1/Brm-associated factor (BAF) chromatin remodeling complex directly binds the CD4 silencer and is essential for CD4 repressigg during T-cell development, because deletion of the ATPase subunit Brg1 or a dominant negative mutant of BAF57 each impairs CD4 repression in early thymocytes. Paradoxically, BAF57 is dispensable for remodeling nucleosomes in vitro or for binding of the BAF complex to the CD4 silencer in vivo. Thus, it is unclear whether BAF57-dependent CD4 repression involves chromatin remodeling and, if so, how the remodeling translates into CD4 repression. Here we show that nucleosomes at the CD4 silencer occupy multiple translational frames. BAF57 dominant negative mutant does not alter these frames, but reduces the accessibility of the entire silencer without affecting the flanking regions, concomitant with localized accumulation of linker histone H1 and eviction of Runx1, a key repressor of CD4 transcription that directly binds the CD4 silencer. Our data indicate that precise nucleosome positioning is not critical for the CD4 silencer function and that BAF57 participates in remodeling H1-containing chromatin at the CD4 silencer, which enables Runx1 to access the silencer and repress CD4. In addition to BAF57, multiple other subunits in the BAF complex are also dispensable for chromatin remodelling in vitro. Our data suggest that these subunits could also help remodel chromatin at a step after the recruitment of the BAF complex to target genes.
AB - The Brg1/Brm-associated factor (BAF) chromatin remodeling complex directly binds the CD4 silencer and is essential for CD4 repressigg during T-cell development, because deletion of the ATPase subunit Brg1 or a dominant negative mutant of BAF57 each impairs CD4 repression in early thymocytes. Paradoxically, BAF57 is dispensable for remodeling nucleosomes in vitro or for binding of the BAF complex to the CD4 silencer in vivo. Thus, it is unclear whether BAF57-dependent CD4 repression involves chromatin remodeling and, if so, how the remodeling translates into CD4 repression. Here we show that nucleosomes at the CD4 silencer occupy multiple translational frames. BAF57 dominant negative mutant does not alter these frames, but reduces the accessibility of the entire silencer without affecting the flanking regions, concomitant with localized accumulation of linker histone H1 and eviction of Runx1, a key repressor of CD4 transcription that directly binds the CD4 silencer. Our data indicate that precise nucleosome positioning is not critical for the CD4 silencer function and that BAF57 participates in remodeling H1-containing chromatin at the CD4 silencer, which enables Runx1 to access the silencer and repress CD4. In addition to BAF57, multiple other subunits in the BAF complex are also dispensable for chromatin remodelling in vitro. Our data suggest that these subunits could also help remodel chromatin at a step after the recruitment of the BAF complex to target genes.
KW - BAF27
KW - CD4
KW - Chromatin
UR - http://www.scopus.com/inward/record.url?scp=60749093350&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=60749093350&partnerID=8YFLogxK
U2 - 10.1002/eji.200838909
DO - 10.1002/eji.200838909
M3 - Article
C2 - 19180471
AN - SCOPUS:60749093350
VL - 39
SP - 580
EP - 588
JO - European Journal of Immunology
JF - European Journal of Immunology
SN - 0014-2980
IS - 2
ER -