Identification of small RNA pathway genes using patterns of phylogenetic conservation and divergence.

Genetic and biochemical analyses of RNA interference (RNAi) and microRNA (miRNA) pathways have revealed proteins such as Argonaute and Dicer as essential cofactors that process and present small RNAs to their targets. Well-validated small RNA pathway cofactors such as these show distinctive patterns of conservation or divergence in particular animal, plant, fungal and protist species. We compared 86 divergent eukaryotic genome sequences to discern sets of proteins that show similar phylogenetic profiles with known small RNA cofactors.

The Caenorhabditis elegans SOMI-1 zinc finger protein and SWI/SNF promote regulation of development by the mir-84 microRNA.

Hundreds of microRNAs (miRNAs) have been discovered in metazoans and plants, and understanding of their biogenesis has advanced dramatically; however, relatively little is known about the cofactors necessary for miRNA regulation of target gene expression. In Caenorhabditis elegans, the conserved miRNA let-7 and its paralogs, including mir-84, control the timing of stage-specific developmental events. To identify factors required for the activity of mir-84 and possibly other miRNAs, we screened for mutations that suppress the developmental defects caused by overexpression of mir-84.

The mir-84 and let-7 paralogous microRNA genes of Caenorhabditis elegans direct the cessation of molting via the conserved nuclear hormone receptors NHR-23 and NHR-25.

The let-7 microRNA (miRNA) gene of Caenorhabditis elegans controls the timing of developmental events. let-7 is conserved throughout bilaterian phylogeny and has multiple paralogs. Here, we show that the paralog mir-84 acts synergistically with let-7 to promote terminal differentiation of the hypodermis and the cessation of molting in C.

Identification of many microRNAs that copurify with polyribosomes in mammalian neurons.

Localized translation in mammalian dendrites may play a role in synaptic plasticity and contribute to the molecular basis for learning and memory. The regulatory mechanisms that control localized translation in neurons are not well understood. We propose a role for microRNAs (miRNAs), a class of noncoding RNAs, as mediators of neuronal translational regulation.

Computational and experimental identification of C. elegans microRNAs.

MicroRNAs (miRNAs) constitute an extensive class of noncoding RNAs that are thought to regulate the expression of target genes via complementary base-pair interactions. To date, cloning has identified over 200 miRNAs from diverse eukaryotic organisms. Despite their success, such biochemical approaches are skewed toward identifying abundant miRNAs, unlike genome-wide, sequence-based computational predictions.