DNA methylation requires a DNMT1 ubiquitin interacting motif (UIM) and histone ubiquitination

Area of Science:

• Epigenetics
• Molecular Biology
• Biochemistry

Background:

• DNA methylation maintenance is crucial for genome stability.
• UHRF1 (Ubiquitin-like, containing PHD and RING finger domains, found in transfers) is a key regulator of DNA methylation.
• DNMT1 (DNA methyltransferase 1) is responsible for maintaining DNA methylation patterns.

Purpose of the Study:

• To elucidate the regulatory mechanisms of DNMT1 recruitment and activity by UHRF1.
• To identify novel interactions and modifications involved in DNA methylation maintenance.
• To characterize the role of histone modifications in recruiting DNMT1.

Main Methods:

• Systematic mutagenesis of UHRF1.
• Functional complementation assays.
• Mass spectrometry to identify ubiquitination targets.
• Bioinformatics and mutational analyses of DNMT1.

Main Results:

• UHRF1 PHD domain binds unmodified H3R2, facilitating chromatin binding.
• UHRF1 ubiquitin ligase activity is essential for DNA methylation maintenance.
• H3K18 is identified as a novel ubiquitination target of UHRF1.
• A DNMT1 UIM binds ubiquitinated H3 tails, crucial for in vivo DNA methylation.
• H3 ubiquitination and DNA methylation depend on UHRF1 PHD binding to H3R2.

Conclusions:

• UHRF1 employs diverse mechanisms, including reading epigenetic marks and histone ubiquitination, to regulate DNMT1.
• A novel DNMT1 UIM mediates interaction with ubiquitinated histones, representing a new regulatory principle.
• This study highlights the intricate interplay between DNA and histone modifications in epigenetic regulation.