PCIF1 Catalyzes m6Am mRNA Methylation to Regulate Gene Expression

Area of Science:

• Molecular Biology
• Epigenetics
• Gene Expression Regulation

Background:

• mRNA modifications are crucial for gene expression control.
• N6,2-O-dimethyladenosine (m6Am) is a prevalent mRNA modification.
• The enzymes and biological roles of m6Am remain largely uncharacterized.

Purpose of the Study:

• To identify the enzyme responsible for m6Am methylation.
• To map the transcriptome-wide distribution of m6Am.
• To elucidate the functional impact of m6Am on gene expression.

Main Methods:

• In vitro and in vivo enzymatic assays to characterize PCIF1 activity.
• Development of m6Am-Exo-Seq for transcriptome-wide m6Am mapping.
• Analysis of mRNA transcription, stability, and translation following m6Am modification.

Main Results:

• PCIF1 identified as the sole human mRNA m6Am methyltransferase.
• PCIF1 specifically catalyzes 5' m6Am methylation of capped mRNAs.
• m6Am distribution is distinct from m6A, with no global crosstalk observed.
• m6Am negatively regulates cap-dependent translation without affecting mRNA transcription or stability.

Conclusions:

• PCIF1 is an evolutionarily conserved methyltransferase for 5' m6Am.
• m6Am acts as a distinct epigenetic mark regulating translation.
• PCIF1-mediated m6Am methylation provides a novel mechanism for gene expression control.