Molecular Biology

Untranslated Regulators

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Science  22 Jan 2010:
Vol. 327, Issue 5964, pp. 394
DOI: 10.1126/science.327.5964.394-a
CREDIT: ROBINE ET AL., CURR. BIOL. 19, 2066 (2009)

A variety of short noncoding RNA molecules—microRNAs, small interfering RNAs, and Piwi-interacting RNAs (piRNAs)—play regulatory roles in eukaryotes. Many piRNAs are derived from transposon-related sequences and, through complementary sequence interactions and a “ping-pong” amplification process, act to silence those selfish and potentially mutagenic elements in germline cells.

However, Robine et al. show that a substantial population of piRNAs found in a Drosophila somatic ovarian cell line are in fact derived from a distinct subset of genes, and also that the bulk of these piRNAs arise directly from the 3′ untranslated regions (3′ UTRs) of the sense strands. This suggests that the complementary targets of these piRNAs may not be the parental transcripts. Ping-pong amplification is not required for the generation of these 3′ UTR piRNAs, nor does it appear as if they are aberrant products of the primary piRNA processing pathway. Furthermore, Saito et al. have found that the Drosophila gene traffic jam (tj) gives rise to 3′ UTR piRNAs and that one of its targets is the fasciclin III gene transcript, and Robine et al. note that the subset of functional categories of mRNAs that gives rise to the 3′ UTR piRNAs is broadly conserved between fruit flies and mice.

Curr. Biol. 19, 2066 (2009); Nature 461, 1296 (2009).

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