Discovery and Functional Understanding of MiRNAs in Mollusks: A Genome-wide Profiling Approach

Small non-coding RNAs play a pivotal role in gene regulation, repression of transposable element and viral activity in various organisms. Among the various categories of these small non-coding RNAs, microRNAs (miRNAs) guide post-translational gene regulation in cellular development, proliferation, apoptosis, oncogenesis, and differentiation. Here, we performed a genome-wide computational prediction of miRNAs to improve the understanding of miRNA observation and function in mollusks. As an initial step, hundreds of conserved miRNAs were predicted in 35 species of mollusks through genome scanning. Afterward, the miRNAs’ population, isoforms, organization, and function were characterised in detail. Furthermore, the key miRNA biogenesis factors, including AGO2, DGCR8, DICER, DROSHA, TRABP2, RAN, and XPO5, were elucidated based on homologue sequence searching. We also summarized the miRNAs’ function in biomineralization, immune and stress response, as well as growth and development in mollusks. Because miRNAs play a vital role in various lifeforms, this study will provide insight into miRNA biogenesis and function in mollusks, as well as other invertebrates.