Mammalian cells contain numerous non-protein-encoding RNA transcripts, many of which are longer than 200 nucleotides. Recent studies indicate that these long non-protein-coding RNAs (lncRNAs) contribute to the complex gene networks that, by regulating gene expression, regulate cellular function. Here (p. 3734), Kannanganattu Prasanth and colleagues identify a new class of mammalian polypurine-repeat-rich lncRNA. These GAA-repeat-containing RNAs (GRC-RNAs), the authors report, are heterogeneous in size, ranging from about 1.5 kb to about 4 kb, and are distributed throughout the nucleus in punctate foci. They show that GRC-RNAs associate with the nuclear matrix and interact with several nuclear-matrix-associated proteins. Furthermore, the localisation, number and size of nuclear GRC-RNA foci change according to the cellular state. Thus, differentiating tissue culture cells contain fewer but larger GRC-RNA foci than proliferating cells, and the number of foci increases during cellular transformation. Based on their results, the authors propose that GRC-RNAs are a new family of mammalian lncRNAs that play crucial roles in the maintenance of the nuclear matrix and/or regulate gene expression.
- © 2010.