Functional characterization of UHRF1 variants in facilitating DNA methylation

Area of Science:

• Epigenetics
• Molecular Biology
• Genetics

Background:

• Ubiquitin-like with PHD and RING finger domains 1 (UHRF1) is crucial for maintaining DNA methylation patterns.
• Previous studies on UHRF1 variants yielded conflicting results due to cellular toxicity and adaptive responses.
• Mouse embryonic stem cells (mESCs) offer a unique model for studying UHRF1 function due to their tolerance of DNA methylation loss.

Purpose of the Study:

• To evaluate the functional consequences of clinical UHRF1 mutations, isoform variations, and epitope tagging.
• To resolve inconsistencies in the characterization of UHRF1 variants.

Main Methods:

• Utilized rescue experiments in Uhrf1-deficient mESCs.
• Characterized UHRF1 mutations found in patients with ICF syndrome.
• Assessed the impact of N-terminal modifications and isoform variation on UHRF1 activity.
• Employed AlphaFold3 for structural predictions.

Main Results:

• The R618X mutation in UHRF1 acts as a null allele, while R296W is hypomorphic.
• N-terminal tagging of UHRF1 completely abolishes its function.
• Human UHRF1 isoform 2, with an N-terminal extension, is functionally inactive.
• Structural predictions indicate N-terminal extensions disrupt inter-domain interactions.

Conclusions:

• This study precisely defines the functional activity of various UHRF1 variants.
• The findings clarify discrepancies in previous UHRF1 research.
• Understanding UHRF1 variant function is critical for epigenetic inheritance studies.