ANOTHER ROLE FOR RNA

Abstract

IN ADDITION TO SILENCING gene expression, short pieces of double-stranded RNA may be able to activate gene expression. To activate gene expression, David R. Corey, Bethany A. Janowski, and coworkers at the University of Texas Southwestern Medical Center, Dallas, use RNA duplexes that target a portion of genomic DNA up-stream from the site where gene transcription begins ( Nat. Chem. Biol., DOI: 10.1038/nchem bio86O). The effect requires that the RNA duplex's sequence be complementary to that of the targeted genomic DNA. Although structurally similar to the RNA used in RNA interference, these RNA duplexes target DNA instead of messenger RNA. The researchers first saw inklings of the effect when they were studying similar DNA-targeting RNAs that reduce the expression of the progesterone receptor (C&EN, Aug. 8,2005, page 10). Some of those RNAs increased gene expression rather than silencing it, but the cell line they were using at the time produced so much progesterone receptor to begin ...