[PDF][PDF] Beyond secondary structure: primary-sequence determinants license pri-miRNA hairpins for processing

VC Auyeung, I Ulitsky, SE McGeary, DP Bartel - Cell, 2013 - cell.com
Cell, 2013cell.com
To use microRNAs to downregulate mRNA targets, cells must first process these∼ 22 nt
RNAs from primary transcripts (pri-miRNAs). These transcripts form RNA hairpins important
for processing, but additional determinants must distinguish pri-miRNAs from the many other
hairpin-containing transcripts expressed in each cell. Illustrating the complexity of this
recognition, we show that most Caenorhabditis elegans pri-miRNAs lack determinants
required for processing in human cells. To find these determinants, we generated many …
Summary
To use microRNAs to downregulate mRNA targets, cells must first process these ∼22 nt RNAs from primary transcripts (pri-miRNAs). These transcripts form RNA hairpins important for processing, but additional determinants must distinguish pri-miRNAs from the many other hairpin-containing transcripts expressed in each cell. Illustrating the complexity of this recognition, we show that most Caenorhabditis elegans pri-miRNAs lack determinants required for processing in human cells. To find these determinants, we generated many variants of four human pri-miRNAs, sequenced millions that retained function, and compared them with the starting variants. Our results confirmed the importance of pairing in the stem and revealed three primary-sequence determinants, including an SRp20-binding motif (CNNC) found downstream of most pri-miRNA hairpins in bilaterian animals, but not in nematodes. Adding this and other determinants to C. elegans pri-miRNAs imparted efficient processing in human cells, thereby confirming the importance of primary-sequence determinants for distinguishing pri-miRNAs from other hairpin-containing transcripts.
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