Dataset Information

The evolution of evolvability in microRNA target sites in vertebrates.

ABSTRACT: The lack of long-term evolutionary conservation of microRNA (miRNA) target sites appears to contradict many analyses of their functions. Several hypotheses have been offered, but an attractive one-that the conservation may be a function of taxonomic hierarchy (vertebrates, mammals, primates, etc.)-has rarely been discussed. For such an analysis, we cannot use evolutionary conservation as a criterion of target identification, and hence, have used high confidence target sites in the cross-linking immunoprecipitation (CLIP) data. Assuming that a proportion, p, of target sites in the CLIP data are conserved, we define the evolvability of miRNA targets as 1-p. Genomic data from vertebrate species show that the evolvability between human and fish is very high, at more than 90%. The evolvability decreases to 50% between birds and mammals, 20% among mammalian orders, and only 6% between human and chimpanzee. Within each taxonomic hierarchy, there is a set of targets that are conserved only at that level of evolution. Extrapolating the evolutionary trend, we find the evolvability in any single species to be close to 0%. Thus, all miRNA target sites identified by the CLIP method are evolutionarily conserved in one species, but the conservation is lost step by step in larger taxonomic groups. The changing evolvability of miRNA targets suggests that miRNA-target interactions may play a role in the evolution of organismal diversity.

SUBMITTER: Xu J

PROVIDER: S-EPMC3814881 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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The evolution of evolvability in microRNA target sites in vertebrates.

Xu Jin J Zhang Rui R Shen Yang Y Liu Guojing G Lu Xuemei X Wu Chung-I CI

Genome research 20130927 11

The lack of long-term evolutionary conservation of microRNA (miRNA) target sites appears to contradict many analyses of their functions. Several hypotheses have been offered, but an attractive one-that the conservation may be a function of taxonomic hierarchy (vertebrates, mammals, primates, etc.)-has rarely been discussed. For such an analysis, we cannot use evolutionary conservation as a criterion of target identification, and hence, have used high confidence target sites in the cross-linking ...[more]

PMID: 24077390

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Project description:MicroRNAs (miRNAs) control the abundance of the majority of the vertebrate transcriptome. The recognition sequences, or target sites, for bilaterian miRNAs are found predominantly in the 3' untranslated regions (3'UTRs) of mRNAs, and are amongst the most highly conserved motifs within 3'UTRs. However, little is known regarding the evolutionary pressures that lead to loss and gain of such target sites. Here, we quantify the selective pressures that act upon miRNA target sites. Notably, selective pressure extends beyond deeply conserved binding sites to those that have undergone recent substitutions. Our approach reveals that even amongst ancient animal miRNAs, which exert the strongest selective pressures on 3'UTR sequences, there are striking differences in patterns of target site evolution between miRNAs. Considering only ancient animal miRNAs, we find three distinct miRNA groups, each exhibiting characteristic rates of target site gain and loss during mammalian evolution. The first group both loses and gains sites rarely. The second group shows selection only against site loss, with site gains occurring at a neutral rate, whereas the third loses and gains sites at neutral or above expected rates. Furthermore, mutations that alter the strength of existing target sites are disfavored. Applying our approach to individual transcripts reveals variation in the distribution of selective pressure across the transcriptome and between miRNAs, ranging from strong selection acting on a small subset of targets of some miRNAs, to weak selection on many targets for other miRNAs. miR-20 and miR-30, and many other miRNAs, exhibit broad, deeply conserved targeting, while several other comparably ancient miRNAs show a lack of selective constraint, and a small number, including mir-146, exhibit evidence of rapidly evolving target sites. Our approach adds valuable perspective on the evolution of miRNAs and their targets, and can also be applied to characterize other 3'UTR regulatory motifs.

Dataset Information

The evolution of evolvability in microRNA target sites in vertebrates.

Publications

The evolution of evolvability in microRNA target sites in vertebrates.

Similar Datasets

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