Most Caenorhabditis elegans microRNAs Are Individually Not Essential for Development or Viability

Abstract

MicroRNAs (miRNAs), a large class of short noncoding RNAs found in many plants and animals, often act to post-transcriptionally inhibit gene expression. We report the generation of deletion mutations in 87 miRNA genes in Caenorhabditis elegans, expanding the number of mutated miRNA genes to 95, or 83% of known C. elegans miRNAs. We find that the majority of miRNAs are not essential for the viability or development of C. elegans, and mutations in most miRNA genes do not result in grossly abnormal phenotypes. These observations are consistent with the hypothesis that there is significant functional redundancy among miRNAs or among gene pathways regulated by miRNAs. This study represents the first comprehensive genetic analysis of miRNA function in any organism and provides a unique, permanent resource for the systematic study of miRNAs.

Determination of the Human Cardiomyocyte mRNA and miRNA Differentiation Network by Fine-Scale Profiling

“…For example, deletions of each miRNA gene individually in Caenorhabditis elegans results in few, if any, phenotypic consequences [49]. Yet miRNAs clearly play an important role in development since the deletion of the miRNA-processing machinery leads to early embryonic lethality in many higher species [5,6].…”

mir-35 is involved in intestine cell G1/S transition and germ cell proliferation in C. elegans

“…In C. elegans, there are currently about 170 miRNA genes listed in the miRBase sequence database (http:// www.mirbase.org); however, only a few have been studied in detail [5][6][7][8][9][10][11][12][13][14]. Because deleting most miRNAs individually does not lead to any overt phenotypes/ abnormalities in development and differentiation [15], it has been a popular accord that functional redundancy of different miRNAs (miRNAs share the same or have diverse and overlapping target mRNAs) may contribute to the limited progress of miRNA study in the worm. The complexity of functional redundancy of miRNAs may further be contributed by tandem-arrayed miRNA gene clusters in the worm genome.…”

Identification of microprocessor-dependent cancer cells allows screening for growth-sustaining micro-RNAs

“…In contrast, blocking the micro-RNA pathway of embryonic stem (ES) cells impaired their growth (Murchison et al, 2005;Wang et al, 2007;Qi et al, 2009). This global approach allowed to circumvent the often silent phenotype observed after inhibition of individual micro-RNAs (Miska et al, 2007;Wang et al, 2008), a probable consequence of the structural and functional redundancy of these regulatory RNAs. In an elegant approach, Wang et al, (2008) went on by complementing this growth defect with individual micro-RNAs.…”