Weaver Syndrome-Associated EZH2 Protein Variants Show Impaired Histone Methyltransferase Function In Vitro.

Area of Science:

• Genetics
• Molecular Biology
• Developmental Biology

Background:

• Weaver syndrome (WS) is a rare overgrowth disorder with characteristic features.
• De novo mutations in enhancer of zeste homolog 2 (EZH2) are implicated in WS etiology.
• EZH2 is crucial for gene regulation as part of the Polycomb-Repressive Complex 2 (PRC2).

Purpose of the Study:

• To functionally characterize WS-associated EZH2 mutations.
• To investigate the impact of these mutations on EZH2's histone methyltransferase activity.
• To explore the relationship between EZH2 function and WS phenotypic variability.

Main Methods:

• In vitro functional assays using artificially assembled PRC2 complexes.
• Incorporation of mutagenized human EZH2 reflecting WS-specific codon changes.
• Assessment of histone methyltransferase activity of mutant EZH2 variants.

Main Results:

• WS-associated EZH2 mutations were found to reduce histone methyltransferase function in vitro.
• The findings support the hypothesis that impaired EZH2 function causes WS.
• Histone methyltransferase activity levels did not directly correlate with phenotypic variability in WS patients.

Conclusions:

• Constitutional mutations in EZH2 impair its histone methyltransferase function, leading to Weaver syndrome.
• The specific mechanism linking EZH2 dysfunction to the spectrum of WS symptoms requires further investigation.
• EZH2's role in epigenetic regulation is critical for normal development, and its disruption leads to overgrowth disorders.