Conservation of the sequence and temporal expression of let-7 heterochronic regulatory RNA

Abstract

Two small RNAs regulate the timing of Caenorhabditis elegans development. Transition from the first to the second larval stage fates requires the 22-nucleotide lin-4 RNA, and transition from late larval to adult cell fates requires the 21-nucleotide let-7 RNA. The lin-4 and let-7 RNA genes are not homologous to each other, but are each complementary to sequences in the 3' untranslated regions of a set of protein-coding target genes that are normally negatively regulated by the RNAs. Here we have detected let-7 RNAs of approximately 21 nucleotides in samples from a wide range of animal species, including vertebrate, ascidian, hemichordate, mollusc, annelid and arthropod, but not in RNAs from several cnidarian and poriferan species, Saccharomyces cerevisiae, Escherichia coli or Arabidopsis. We did not detect lin-4 RNA in these species. We found that let-7 temporal regulation is also conserved: let-7 RNA expression is first detected at late larval stages in C. elegans and Drosophila, at 48 hours after fertilization in zebrafish, and in adult stages of annelids and molluscs. The let-7 regulatory RNA may control late temporal transitions during development across animal phylogeny.

Comprehensive analysis of microRNA expression patterns in hepatocellular carcinoma and non-tumorous tissues

“…The sequences of many miRNAs are conserved between distantly related organisms, suggesting that these molecules participate in essential processes (Pasquinelli et al, 2000;Ke et al, 2003;Moss, 2003). Although the precise biological functions of miRNAs are not yet fully understood, they have diverse expression patterns and may regulate various developmental and physiological processes.…”

MiRNA expression analysis during normal zebrafish development and following inhibition of the Hedgehog and Notch signaling pathways

“…Direct cloning strategies and bioinformatic prediction based on the presence of conserved hairpin structures and sequences have suggested that animal genomes encode hundreds, perhaps thousands, of microRNAs (Lagos-Quintana et al, 2001;Lau et al, 2001;Lee and Ambros, 2001;Lai et al, 2003;Lim et al, 2003a;Lim et al, 2003b;Kim and Nam, 2006). These small RNAs regulate early development, cell specification, differentiation, and proliferation (Lee et al, 1993;Pasquinelli et al, 2000;Reinhart et al, 2000;Ambros, 2003;Bartel, 2004;Griffiths-Jones, 2004;Hobert, 2004;Du and Zamore, 2005;Hatfield et al, 2005;Morris and McManus, 2005;O'Donnell et al, 2005;Carthew, 2006;Esquela-Kerscher and Slack, 2006;Naguibneva et al, 2006;Plasterk, 2006;Slack and Weidhaas, 2006;Voorhoeve et al, 2006).…”

IGF2‐derived miR‐483‐3p associated with Hirschsprung's disease by targeting FHL1

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