Depletion of the chromatin remodeler CHD4 sensitizes AML blasts to genotoxic agents and reduces tumor formation.

Chromodomain helicase DNA-binding protein 4 (CHD4) is an ATPase that alters the phasing of nucleosomes on DNA and has recently been implicated in DNA double-stranded break (DSB) repair. Here, we show that depletion of CHD4 in acute myeloid leukemia (AML) blasts induces a global relaxation of chromatin that renders cells more susceptible to DSB formation, while concurrently impeding their repair. Furthermore, CHD4 depletion renders AML blasts more sensitive both in vitro and in vivo to genotoxic agents used in clinical therapy: daunorubicin (DNR) and cytarabine (ara-C).

Mi2β-mediated silencing of the fetal γ-globin gene in adult erythroid cells.

An understanding of the human fetal to adult hemoglobin switch offers the potential to ameliorate β-type globin gene disorders such as sickle cell anemia and β-thalassemia through activation of the fetal γ-globin gene. Chromatin modifying complexes, including MBD2-NuRD and GATA-1/FOG-1/NuRD, play a role in γ-globin gene silencing, and Mi2β (CHD4) is a critical component of NuRD complexes. We observed that knockdown of Mi2β relieves γ-globin gene silencing in β-YAC transgenic murine chemical inducer of dimerization hematopoietic cells and in CD34(+) progenitor-derived human primary adult erythroid cells.

Methyl-binding domain protein 2-dependent proliferation and survival of breast cancer cells.

Methyl cytosine binding domain protein 2 (MBD2) has been shown to bind to and mediate repression of methylated tumor suppressor genes in cancer cells, where repatterning of CpG methylation and associated gene silencing is common. We have investigated the role of MBD2 in breast cancer cell growth and tumor suppressor gene expression. We show that stable short hairpin RNA (shRNA)-mediated knockdown of MBD2 leads to growth suppression of cultured human mammary epithelial cancer lines, SK-BR-3, MDA-MB-231, and MDA-MB-435.

p66Alpha-MBD2 coiled-coil interaction and recruitment of Mi-2 are critical for globin gene silencing by the MBD2-NuRD complex.

Nucleosome remodeling complexes comprise several large families of chromatin modifiers that integrate multiple epigenetic control signals to play key roles in cell type-specific transcription regulation. We previously isolated a methyl-binding domain protein 2 (MBD2)-containing nucleosome remodeling and deacetylation (NuRD) complex from primary erythroid cells and showed that MBD2 contributes to DNA methylation-dependent embryonic and fetal β-type globin gene silencing during development in vivo. Here we present structural and biophysical details of the coiled-coil interaction between MBD2 and p66α, a critical component of the MBD2-NuRD complex.

Differential IFN-gamma stimulation of HLA-A gene expression through CRM-1-dependent nuclear RNA export.

IFNs regulate most MHC class I genes by stimulating transcription initiation. As shown previously, IFN-gamma controls HLA-A expression primarily at the posttranscriptional level. We have defined two 8-base sequences in a 39-nucleotide region in the 3'-transcribed region of the HLA-A gene that are required for the posttranscriptional response to IFN-gamma.

MBD2 is a critical component of a methyl cytosine-binding protein complex isolated from primary erythroid cells.

The chicken embryonic beta-type globin gene, rho, is a member of a small group of vertebrate genes whose developmentally regulated expression is mediated by DNA methylation. Previously, we have shown that a methyl cytosine-binding complex binds to the methylated rho-globin gene in vitro. We have now chromatographically purified and characterized this complex from adult chicken primary erythroid cells.

Methylation of promoter proximal-transcribed sequences of an embryonic globin gene inhibits transcription in primary erythroid cells and promotes formation of a cell type-specific methyl cytosine binding complex.

The methylation pattern of a 248-base pair proximal transcribed region (rho248) of the avian embryonic rho-globin gene was found to correlate inversely with stage-specific expression in avian erythroid cells. In vitro methylation of the rho248 segment alone (in the absence of promoter methylation) resulted in a 5-fold inhibition of transcription in a transient transfection assay in primary erythroid cells in which the transfected gene is packaged into nucleosomal chromatin. This effect was observed if the rho248 segment was positioned adjacent to the promoter but not when it was located 2.