The human enhancer blocker CTC-binding factor interacts with the transcription factor Kaiso

Area of Science:

• Genomics
• Molecular Biology
• Epigenetics

Background:

• The CTCF-binding factor (CTCF) is a vertebrate DNA-binding protein crucial for genome regulation, functioning as an enhancer blocker.
• Identifying CTCF-interacting proteins is key to understanding the regulation of its genomic functions.

Purpose of the Study:

• To identify protein partners of CTCF that may regulate its enhancer-blocking activity.
• To investigate the functional consequences of the interaction between CTCF and its newly identified partner, Kaiso.

Main Methods:

• Yeast two-hybrid screening was employed to identify CTCF-interacting proteins.
• Co-immunoprecipitation assays were used to confirm the interaction between CTCF and Kaiso in nuclear lysates.
• Insulation assays were performed to assess the impact of Kaiso binding on CTCF's enhancer-blocking activity.

Main Results:

• Kaiso, a POZ-zinc finger transcription factor, was identified as a specific binding partner of CTCF.
• The interaction between CTCF and Kaiso was confirmed through co-immunoprecipitation.
• The presence of a Kaiso binding site near a CTCF binding site reduced CTCF's enhancer-blocking activity in an insulation assay.

Conclusions:

• The interaction between Kaiso and CTCF negatively regulates CTCF's insulator activity.
• Kaiso acts as a modulator of CTCF-mediated genome regulation.