Multiple distinct small RNAs originate from the same microRNA precursors

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• MicroRNAs (miRNAs) are crucial regulators of gene expression in eukaryotes, derived from precursor transcripts with stem-loop structures.
• The biogenesis and regulatory roles of miRNAs are well-established, but the full extent of their diversity is still being explored.

Purpose of the Study:

• To investigate the potential for miRNA precursors to generate additional small RNAs beyond canonical miRNAs and miRNA*s.
• To characterize the biogenesis, properties, and potential functions of these novel miRNA-like RNAs.
• To determine the prevalence of these miRNA-like RNAs across different eukaryotic species.

Main Methods:

• Analysis of small RNA sequencing data from Arabidopsis thaliana.
• Identification and characterization of miRNA precursors yielding multiple distinct small RNAs.
• Assessment of miRNA-like RNA production, methylation, Argonaute association, and expression patterns.
• Computational and degradome analyses to predict and validate targets.
• Systematic examination of public small RNA data from diverse plant and animal species.

Main Results:

• Identified 19 miRNA precursors in Arabidopsis capable of producing multiple distinct miRNA-like RNAs alongside canonical miRNAs and miRNA*s.
• These miRNA-like RNAs are produced via the standard miRNA biogenesis pathway, are methylated, and associate with Argonaute proteins.
• Demonstrated that these miRNA-like RNAs are conserved across various eukaryotic species, including plants and animals.
• Found evidence that some miRNA-like RNAs are differentially expressed, potentially target protein-coding genes, and their function is supported by target cleavage data.

Conclusions:

• Multiple miRNAs and miRNA-like RNAs can be generated from single miRNA precursors through sequential processing by Dicer or Dicer-like proteins.
• The repertoire of functional small RNAs involved in gene regulation is larger than previously understood.
• miRNA-mediated gene regulation is more complex and potentially broader in scope than previously recognized.