Cancer mutations rewire the RNA methylation specificity of METTL3-METTL14

Area of Science:

• Molecular Biology
• Epigenetics
• Cancer Research

Background:

• Chemical modification of RNAs, particularly N6-methyladenosine (m6A), is crucial for posttranscriptional gene regulation.
• The METTL3-METTL14 complex is the primary enzyme responsible for m6A methylation in messenger RNAs (mRNAs).
• Aberrant expression of methyltransferases, including METTL14, is implicated in the development of various cancers.

Purpose of the Study:

• To investigate how a specific METTL14 mutation (METTL14R298P) found in cancer patients influences RNA methylation and oncogenesis.
• To determine the sequence context preference of the mutant METTL14 methyltransferase.
• To elucidate the impact of altered m6A modification patterns on cancer cell behavior.

Main Methods:

• Biochemical assays to assess methyltransferase activity and substrate specificity.
• In vitro and in vivo experiments using cell cultures and transgenic mice.
• Structural analysis to model RNA sequence selection by the METTL3-METTL14 complex.
• Analysis of m6A detection by YTH readers and demethylation by ALKBH5.

Main Results:

• The METTL14R298P mutation promotes malignant cell growth without increasing global mRNA m6A levels.
• The mutant methyltransferase exhibits a preference for noncanonical GGAU motifs for m6A modification.
• m6A modifications in the GGAU context are recognized by YTH readers but are less efficiently demethylated by ALKBH5.
• A model was developed explaining RNA sequence selection by the METTL3-METTL14 complex.

Conclusions:

• Sequence-specific m6A deposition plays a significant role in gene regulation and oncogenesis.
• Increased m6A methylation at GGAU sites, driven by the METTL14R298P mutation, can promote cancer progression.
• Understanding altered m6A patterns offers potential therapeutic targets for cancer treatment.