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S010
Multiple products from microRNA transcripts
Sam Griffiths-Jones
University of Manchester, Manchester, United Kingdom
Primary transcripts of microRNAs can produce multiple functional
products. For example, around a half of mammalian microRNAs
are located in introns of protein-coding genes. In these cases,
the microRNA and the protein-coding mRNA are processed
from the same transcript. Similarly, around a third of animal
microRNAs are located in close proximity in the genome to other
microRNAs. Here, one transcript may be processed to produce
multiple functional microRNA sequences. In addition, each
microRNA precursor hairpin has the potential to produce two
different mature microRNAs. We have investigated the evolutionary and functional relationships between the multiple products of
microRNA transcripts. We find the most common mechanism for
the formation of multi-product transcripts is de novo microRNA
birth in transcribed regions. These regions include introns of protein-coding genes, pre-existing primary microRNA transcripts, and
transcripts produced from divergent promoters. The expression
of microRNA transcripts that produce multiple products is under
tighter regulatory control than other gene products. However,
mature microRNAs processed from the same transcript target
different genes and different pathways. We therefore suggest that
microRNA transcripts that produce multiple products have multiple
functions.