Towards an understanding of cell-specific functions of signal-dependent transcription factors

  1. Christopher K Glass1,3
  1. 1Department of Cellular and Molecular Medicine
    2Biomedical Sciences Graduate Program
    3Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, USA
  1. Correspondence should be addressed to C K Glass; Email: ckg{at}
  1. Figure 1

    Hierarchical organization of transcription factor networks. In the poised or repressed state, closed chromatin at enhancer loci contains motifs for LDTFs. The collaborative binding of LDTFs such as PU.1 and C/EBPs results in nucleosomal-remodeling and basal enhancer RNA transcription at sites containing low H3K4me1/2 and low H3/H4 acetylation. Next, in response to various stimuli, SDTFs, such as LXRs, co-bind with PU.1 and C/EBPs to activate enhancer transcription. Finally, activated eRNA transcription precedes the active deposition of H3K4me1/2 and H3/H4 acetylation. LDTF, lineage-determining transcription factor; SDTF, signal-dependent transcription factor.

  2. Figure 2

    Histone marks at active and poised promoters and enhancers. Promoters are designated by high levels of H3K4me3, while enhancers contain high levels of H3K4me1/2. In the poised or repressed state, promoters contain histone methylation marks, H3K27me3, and H3K20me3, while enhancers contain H3K27me3/me1 and H3K9me1. Active promoters and enhancers are marked by H3K4me2 and H3K27Ac. GTF, general transcription factor; LDTF, lineage-determining transcription factor; SDTF, signal-dependent transcription factor.

  3. Figure 3

    Mechanisms for regulating gene expression in macrophages: coregulator exchange from corepressor to coactivator. In the poised or repressed state, the NCOR1/HDAC3/SMYD5 complex inhibits active transcription through de-acetylation of histone H3 and H4, as well as tri-methylation of H4K20. After signal-dependent recruitment of activating transcription factors such as NF-κB, the NCOR1 complex is exchanged for coactivator complexes that remove repressive marks and acetylate histones H3 and H4, recruiting the P-TEFb complex to activate transcriptional elongation.

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