MicroRNA Biogenesis and Processing Mechanisms

MicroRNAs (miRNAs) are a class of small non-coding RNAs that fine-tune gene expression by guiding effector complexes to complementary messenger RNAs (mRNAs), leading to translational repression or target degradation. Their maturation involves a series of coordinated nuclear and cytoplasmic steps. In the nucleus, primary miRNA transcripts (pri-miRNAs), bearing characteristic stem–loop structures, are recognised and cleaved by the Microprocessor complex—comprising the RNase III enzyme DROSHA and its partner DGCR8—to release precursor miRNAs (pre-miRNAs). These hairpin intermediates are then exported to the cytoplasm by specialised transport receptors, where DICER carries out a second RNase III cleavage to produce a miRNA duplex of approximately 22 nucleotides. One strand of this duplex is loaded into an Argonaute protein within the RNA-induced silencing complex (RISC), forming the active silencing assembly. Throughout this cascade, RNA-binding proteins that target conserved loop motifs or flanking sequences modulate processing efficiency and fidelity, integrating developmental signals, environmental cues and stress responses. Dysregulation of these pathways is implicated in a wide range of human diseases, including cancer, cardiovascular disorders and neurodegenerative conditions, underscoring the global significance of understanding miRNA biogenesis.

Research from Nature Portfolio

Recent studies have introduced programmable RNA devices that confer conditional control over miRNA biogenesis, activating artificial miRNAs only upon binding to defined trigger RNAs in mammalian cells. This innovation demonstrates how de novo-designed cis-repressing elements can achieve up to 30-fold dynamic range in miRNA production, paving the way for cell-type-specific gene regulation and therapeutic applications. Complementary structural work has elucidated how RNA-binding proteins engage terminal loop motifs of specific pri-miRNAs to induce allosteric destabilisation of the stem region, thereby enhancing Microprocessor cleavage precision. Together, these advances reveal general principles for engineering and regulating miRNA maturation with high specificity.

MicroRNA Biogenesis and Processing Mechanisms publication trend

The graph below shows the total number of articles in microrna biogenesis and processing mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

pri-miRNA: A primary transcript bearing one or more hairpin structures that serve as precursors for miRNA production.

Microprocessor: The nuclear complex of DROSHA and DGCR8 that cleaves pri-miRNAs to generate pre-miRNAs.

pre-miRNA: A ∼70 nucleotide hairpin intermediate exported to the cytoplasm for further processing by DICER.

DROSHA: An RNase III enzyme that initiates miRNA processing by cleaving pri-miRNAs within the nucleus.

DGCR8: The double-stranded RNA-binding protein that partners with DROSHA in the Microprocessor complex.

DICER: A cytoplasmic RNase III enzyme that processes pre-miRNAs into miRNA duplexes suitable for incorporation into RISC.

RNA-induced silencing complex (RISC): A multiprotein effector assembly loaded with mature miRNAs to guide sequence-specific gene silencing.

Exportin 5: A nuclear transport receptor that mediates the export of pre-miRNAs to the cytoplasm.

References

1. Conditional RNA interference in mammalian cells via RNA transactivation. Nature Communications (2024).
2. Dissection of the Caenorhabditis elegans Microprocessor. Nucleic Acids Research (2023).
3. Posttranscriptional Regulation of miRNAs Harboring Conserved Terminal Loops. Molecular Cell (2008).
4. Structural basis for terminal loop recognition and stimulation of pri-miRNA-18a processing by hnRNP A1. Nature Communications (2018).
5. Efficient Processing of Primary microRNA Hairpins by Drosha Requires Flanking Nonstructured RNA Sequences*. Journal of Biological Chemistry (2005).
6. Genetic variation and RNA structure regulate microRNA biogenesis. Nature Communications (2017).
7. RNA Binding Proteins in the miRNA Pathway. International Journal of Molecular Sciences (2015).