N-6-Methyladenosine in Vasoactive microRNAs during Hypoxia; A Novel Role for METTL4

Area of Science:

• Molecular Biology
• Epigenetics
• RNA Biology

Background:

• N-6-methyladenosine (m6A) is the most abundant RNA modification in eukaryotes.
• m6A is dynamically regulated by writer and eraser enzymes, influencing mRNA stability, splicing, and microRNA processing.
• Hypoxia-induced changes in m6A impact cellular functions, including heart failure.

Purpose of the Study:

• To investigate vasoactive microRNA m6A methylation in fibroblasts.
• To determine the effect of hypoxia on microRNA m6A levels.
• To identify the specific enzymes responsible for hypoxia-induced m6A changes in microRNAs.

Main Methods:

• m6A immunoprecipitation was used to detect m6A modification in microRNAs.
• Fibroblasts and a human fibroblast cell line were utilized.
• Silencing of m6A writer and eraser enzymes, followed by immunoprecipitation, identified key regulatory enzymes.
• m6A-methylated microRNA mimics were employed to assess functional impact.

Main Results:

• At least 16 out of 19 investigated vasoactive microRNAs showed m6A modification in fibroblasts.
• Hypoxia significantly increased mature microRNA m6A levels.
• METTL4, an snRNA m6A methyltransferase, was identified as the primary enzyme responsible for the hypoxia-induced increase in m6A.
• MicroRNA m6A directly influences the efficacy of downstream target mRNA repression.

Conclusions:

• Vasoactive microRNAs are frequently m6A methylated in fibroblasts.
• Hypoxia dynamically regulates microRNA m6A methylation, with METTL4 playing a key role.
• MicroRNA m6A modification is a significant regulatory mechanism affecting gene expression and cellular responses.