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. Author manuscript; available in PMC: 2011 Apr 11.
Published in final edited form as: Nature. 2011 Jan 20;469(7330):336–342. doi: 10.1038/nature09783

Figure 1. Concepts of miRNA function.

Figure 1

The potential modes of miRNA-based regulation of gene expression are shown. a, Intronic miRNAs are encoded within an intron of a host gene. mRNA splicing generates a protein-coding transcript and an miRNA stem–loop. Intronic miRNAs often regulate similar processes to that of the protein encoded by the host gene. AAA, polyadenylated tail of the transcript; pre-miRNA, precursor miRNA. b, A common mechanism of miRNA function involves the modest repression of several mRNAs in a common biological process by a single miRNA. This mechanism reduces the dependence on a single miRNA-mRNA interaction and increases the robustness of the gene-regulatory network. TF, transcription factor. c, Many miRNAs may cooperatively or redundantly regulate a single biological process, by individually targeting many components of that process or by synergistically repressing a crucial component of a pathway. d, miRNAs may act as a ‘buffer’ against minor perturbations in a biological pathway. This is accomplished by the targeting of factors that positively and negatively influence a particular process, thereby insulating that process from environmental fluctuations.