CTCF binding site sequence differences are associated with unique regulatory and functional trends during embryonic...

Area of Science:

• Molecular Biology
• Genomics
• Developmental Biology

Background:

• CCCTC-binding factor (CTCF) is a crucial genome-wide DNA-binding protein.
• CTCF binding site sequence variations may influence its recruitment and regulatory roles.
• Understanding CTCF's dynamic binding is key to deciphering gene regulation during development.

Purpose of the Study:

• To investigate how variations in CTCF binding site sequences affect CTCF binding and gene expression during mouse embryonic stem cell differentiation.
• To identify specific sequence motifs associated with developmentally regulated CTCF binding.
• To elucidate the distinct regulatory functions of different classes of CTCF binding sites.

Main Methods:

• Genome-wide characterization of CTCF binding and gene expression changes during mouse embryonic stem cell differentiation.
• Classification of CTCF binding sites into LowOc, MedOc, and HighOc based on consensus motif similarity.
• In vitro measurement of CTCF binding affinity to selected DNA sites.
• Comparative analysis of CTCF binding dynamics and gene expression profiles.

Main Results:

• Developmentally regulated CTCF binding predominantly occurs at LowOc sites with lower consensus motif similarity.
• Sites with motifs associated with weaker in vitro CTCF binding are preferentially lost during differentiation.
• Enrichment of 'T' at the 18th position of the CTCF binding site correlates with regulated binding in the LowOc class and reduced CTCF affinity.
• Distinct regulatory roles were identified for LowOc and HighOc CTCF binding sites in relation to gene expression changes.

Conclusions:

• CTCF's regulatory control is significantly influenced by specific motifs within its binding sites.
• Sequence-dependent CTCF binding affinity plays a critical role in regulating gene expression during cellular differentiation.
• The heterogeneity of CTCF binding sites contributes to its diverse functions in genome regulation.