Bovine piRNA-like RNAs are associated with both transposable elements and mRNAs

Area of Science:

• Reproductive Biology
• Genomics
• Molecular Biology

Background:

• PIWI proteins and piRNAs are crucial for genomic integrity in spermatogenesis.
• Emerging evidence suggests PIWI/piRNA system roles beyond gametogenesis, including in somatic tissues, cancers, and early embryos.

Purpose of the Study:

• To investigate the small RNA complement in bovine gonads, gametes, and embryos.
• To characterize piRNA-like RNAs (pilRNAs) in bovine oocytes and zygotes and their potential functions.

Main Methods:

• Next-generation sequencing of small RNAs from bovine tissues.
• Bioinformatic analysis to identify and characterize piRNA populations.
• Comparison of pilRNA targeting with mRNA expression data.

Main Results:

• Distinct piRNA populations were found in testes.
• Bovine oocytes and zygotes contain significant populations of 24-27 nt piRNA-like RNAs (pilRNAs).
• These pilRNAs exhibit canonical piRNA features, target transposons (LINE RTE, ERV1) and specific mRNAs, and show negative correlations with mRNA expression changes during early embryonic development.

Conclusions:

• This study provides the first characterization of the PIWI/piRNA pathway in bovine embryogenesis.
• Oocyte and embryo pilRNAs play a potential role in regulating gene expression and transposon activity during early development.
• The findings highlight the PIWI/piRNA system's expanded role in mammalian embryogenesis.