DNA specificity determinants associate with distinct transcription factor functions | JoVE Visualize

Area of Science:

Molecular Biology
Genomics
Epigenetics

Background:

Transcriptional control networks are built from genomic sequences, but understanding DNA sequence, transcription factor (TF) binding, and function remains challenging.
Consensus-based binding predictions are limited due to degenerate motifs and shared preferences among related TFs, as exemplified by the ETS family TF ETS1.
ETS1 shows redundant occupancy with other ETS proteins at housekeeping gene promoters but has specific functions in T cell activation, suggesting unique targets.

Purpose of the Study:

To identify sequence motifs mediating specific functions of ETS1.
To investigate the genome-wide binding of ETS1 in T cells and its relationship with other regulatory factors.
To differentiate ETS1 binding at promoters versus enhancers and link it to gene function.

Main Methods:

Genome-wide chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) was employed to map ETS1 binding sites in Jurkat T cells.
DNase I sensitivity data were integrated to validate the ChIP-seq dataset and enhance accuracy.
Analysis included comparative occupancy studies with GABPA, RUNX factors, and the co-activator CBP, alongside motif discovery and gene ontology analysis.

Main Results:

ETS1 showed redundant occupancy with GABPA at promoters of housekeeping genes and specific occupancy at enhancers of T cell-specific genes.
Two mechanisms for ETS1 specificity were identified: intrinsic preference for a variant ETS motif and cooperative binding with RUNX factors at composite sites.
Co-activator CBP co-localized with ETS1 at specific enhancers, and distinct sequences predicted promoter/enhancer location and gene ontology.

Conclusions:

ETS1 exhibits distinct binding patterns at promoters and enhancers, mediated by specific DNA sequence motifs and interactions with other TFs like RUNX.
The diversity of DNA binding motifs enables variable transcription factor function at different genomic locations, contributing to complex gene regulation.
These findings provide insights into how transcription factor binding specificity is achieved and how it contributes to cellular functions like T cell activation.