Single-nucleotide Resolution Epitranscriptomic Profiling Uncovers Dynamic m⁶A Regulation in Bovine Preimplantation...

Area of Science:

• Epigenetics and Developmental Biology
• Mammalian Embryogenesis
• RNA Modifications

Background:

• RNA N⁶-methyladenosine (m⁶A) is a key epigenetic regulator of gene expression.
• m⁶A dynamics and functional roles in early mammalian development are not fully understood.
• Previous studies lack single-nucleotide resolution of m⁶A during preimplantation development.

Purpose of the Study:

• To map the comprehensive m⁶A landscape in bovine oocytes and preimplantation embryos at single-nucleotide resolution.
• To identify novel m⁶A modifications critical for early embryonic development.
• To elucidate the functional significance of site-specific m⁶A in key developmental regulators.

Main Methods:

• Utilized SAC-seq, a single-base resolution, antibody-independent m⁶A profiling technique.
• Generated the first comprehensive m⁶A landscape in bovine oocytes and preimplantation embryos.
• Investigated the functional impact of m⁶A modification disruption on embryonic development.

Main Results:

• Identified a previously uncharacterized m⁶A site in the RPL12 transcript crucial for embryonic development.
• Demonstrated that loss of m⁶A at this site reduces protein synthesis and disrupts translation-related gene expression.
• Observed impaired zygotic genome activation and blastocyst formation upon m⁶A disruption.
• Showed that wild-type RPL12 mRNA supplementation could not rescue developmental arrest, highlighting m⁶A's role beyond transcript levels.

Conclusions:

• Provides a valuable single-nucleotide resolution m⁶A landscape resource for mammalian embryogenesis.
• Uncovers a critical mechanism where site-specific m⁶A regulates translation and developmental competence in early embryos.
• Suggests m⁶A modification is essential for precise control of protein synthesis during early development.