MicroRNA Regulation in Marine Invertebrates

MicroRNAs (miRNAs) are short non-coding RNAs that fine-tune gene expression by guiding the degradation or translational repression of target mRNAs. In marine invertebrates, these small regulators orchestrate developmental programmes, innate immune defences and responses to environmental stressors such as salinity shifts, hypoxia and pathogen challenge. Biogenesis of miRNAs involves sequential processing by Drosha and Dicer enzymes, yielding mature ~22-nucleotide molecules that bind complementary sequences in 3′-untranslated regions. Through spatial and temporal control of key transcripts, miRNAs contribute to tissue differentiation, redox homeostasis and the modulation of signalling cascades. Characterisation of miRNA repertoires in bivalves, echinoderms and cnidarians has revealed conserved families alongside lineage-specific species, underscoring both evolutionary continuity and adaptive innovation. Insights into miRNA-mediated networks hold promise for improving aquaculture resilience, monitoring ecosystem health and understanding the molecular basis of invertebrate plasticity under climate change.

Research from Nature Portfolio

High-throughput sequencing of small RNAs in two oyster species subjected to low-salinity challenge has identified over 200 miRNAs in Crassostrea gigas and nearly 90 in C. hongkongensis. A subset of eight miRNAs displayed differential expression in gill tissue, regulating genes linked to microtubule dynamics and cellular component movement, thereby facilitating osmotic acclimation. Verification by quantitative PCR and functional enrichment analysis has illuminated miRNA–mRNA interaction pairs that underpin salinity tolerance in bivalves.

Investigation of sea cucumber Apostichopus japonicus has revealed that miR-133 directly targets an interleukin-1 receptor-associated kinase within the toll-like receptor cascade. Modulation of this kinase by miR-133 enhances coelomocyte phagocytosis upon bacterial exposure, demonstrating a clear role for miRNA in tuning echinoderm innate immunity and pathogen clearance.

MicroRNA Regulation in Marine Invertebrates publication trend

The graph below shows the total number of articles in microrna regulation in marine invertebrates across all publications each year (not limited to Nature Index journals).

Technical terms

MicroRNA (miRNA): Small (~22 nt) non-coding RNA that binds complementary mRNA sequences to repress translation or promote degradation.

Post-transcriptional regulation: Control of gene expression at the RNA level after transcription, including splicing, stability and translation.

3′-untranslated region (3′-UTR): Section of mRNA downstream of the coding sequence that often contains regulatory binding sites for miRNAs and proteins.

Toll-like receptor (TLR): Pattern-recognition receptor that detects conserved pathogen-associated molecules and initiates innate immune signalling.

Coelomocyte: Immune effector cell in echinoderms’ coelomic fluid, involved in phagocytosis and pathogen defence.

Co-expression network analysis: Computational method to identify groups of genes or miRNAs with correlated expression patterns across tissues or conditions.

References

1. High throughput sequencing of small RNAs transcriptomes in two Crassostrea oysters identifies microRNAs involved in osmotic stress response. Scientific Reports (2016).
2. miRNA-133 augments coelomocyte phagocytosis in bacteria-challenged Apostichopus japonicus via targeting the TLR component of IRAK-1 in vitro and in vivo. Scientific Reports (2015).
3. Exploring the Role of a Novel Interleukin-17 Homolog from Invertebrate Marine Mussel Mytilus coruscus in Innate Immune Response: Is Negative Regulation by Mc-Novel_miR_145 the Key?. International Journal of Molecular Sciences (2023).
4. microRNA-mRNA Analysis Reveals Tissue-Specific Regulation of microRNA in Mangrove Clam (Geloina erosa). Biology (2023).