Repressing RNA

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Science  06 Feb 2004:
Vol. 303, Issue 5659, pp. 733
DOI: 10.1126/science.303.5659.733b

Recent discoveries have demonstrated that noncoding RNAs play important roles in an increasingly wide range of biological processes. Although the functions of micro RNAs (miRNAs) are still being explored, the involvement of specific non-coding RNAs in the formation of germ plasm and germ cells has been appreciated for several years, yet, unlike miRNAs, their mode of action has for the most part not been well defined.

One such noncoding RNA is polar granule component (pgc), which is required for germ cell establishment in Drosophila. During germ cell formation, gene expression is shut down for a critical period during embryonic development. Martinho et al. show that the pgc RNA mediates this transcriptional silencing by preventing phosphorylation of the C-terminal domain (CTD) Ser2 residue of RNA polymerase II, an important event that is required for the transition from the pre-initiation transcription complex to the actively transcribing elongation complex. The authors speculate that pgc may function like another noncoding species, the 7SK small nuclear RNA, found in humans, that acts to sequester factors required for the phosphorylation of the CTD Ser2. — GR

Curr. Biol. 14, 159 (2004).

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