Identifying transcription factors with cell-type specific DNA binding signatures

Area of Science:

• Genomics
• Molecular Biology
• Bioinformatics

Background:

• Transcription factors (TFs) are proteins that bind DNA to regulate gene expression.
• TF DNA-binding preferences are generally assumed to be constant across different cell types.
• However, evidence suggests TFs can alter binding preferences or exhibit differential binding signatures based on cell type.

Purpose of the Study:

• To systematically investigate and quantify cell-type specificity in TF DNA-binding preferences.
• To develop a computational method for detecting these cell-type specific binding signatures.

Main Methods:

• Developed SigTFB (Signatures of TF Binding), a deep learning approach.
• Analyzed ENCODE ChIP-seq data for 169 TFs across up to 14 cell types.
• Quantified cell-type specificity in TF genomic binding sites.

Main Results:

• Detected statistically significant DNA binding signatures in approximately two-thirds of TFs studied.
• Found that binding signatures are largely uncorrelated with the overlap of ChIP-seq peaks between cell types.
• Identified two primary mechanisms for signature emergence: differential motif usage frequency and selective inclusion of distinct TF motifs.

Conclusions:

• Emphasizes the importance of DNA sequence motifs in TF binding specificity, complementing other cell state features like chromatin accessibility and gene expression.
• Highlights that TF binding is not solely determined by general binding preferences but can be modulated by cell-type specific sequence contexts.