CHD7 targets active gene enhancer elements to modulate ES cell-specific gene expression.

Area of Science:

• Genetics
• Molecular Biology
• Developmental Biology

Background:

• CHD7 is a key member of the chromodomain helicase DNA-binding domain family involved in ATP-dependent chromatin remodeling.
• De novo mutations in CHD7 are a primary cause of CHARGE syndrome, a complex genetic disorder with multiple congenital anomalies.

Purpose of the Study:

• To investigate the functional role of CHD7 in mammalian cells, specifically its genomic binding sites and regulatory mechanisms.
• To understand how CHD7 influences gene expression, particularly in the context of embryonic stem (ES) cells.

Main Methods:

• Chromatin immunoprecipitation followed by massively parallel DNA sequencing (ChIP-Seq) was employed to map CHD7 binding sites in mouse ES cells.
• Correlation analysis was performed between CHD7 binding sites, epigenetic marks (H3K4 mono-methylation), chromatin accessibility (DNase I hypersensitivity), and gene expression profiles.

Main Results:

• Over 10,000 high-confidence CHD7 binding sites were identified, predominantly located at enhancer elements.
• CHD7 co-localizes with known enhancer-binding proteins (P300) and master ES cell regulators (OCT4, SOX2, NANOG).
• CHD7 acts as a transcriptional rheostat, modulating the expression of ES cell-specific genes in both positive and negative directions, with a stronger direct effect on negative regulation.

Conclusions:

• CHD7 plays a critical role in regulating gene expression at enhancer regions, functioning as a rheostat to fine-tune gene output.
• The findings suggest that enhancer-mediated gene dysregulation by CHD7 may contribute to the pathogenesis of CHARGE syndrome.
• Enhancer-binding proteins can exert repressive roles in gene expression, challenging the notion that they are solely co-activators.