How do ncRNAs guide chromatin-modifying complexes to specific locations within the nucleus?

Abstract

Transcriptome analyses have led to the realisation that eukaryotic cells make a large number of noncoding RNAs (ncRNAs). It appears that some of these are involved in guiding chromatin-modifying complexes to specific locations within the nucleus. How such ncRNAs function is largely unknown but various models have been proposed. Here we briefly discuss the evidence supporting two such models; that ncRNAs function by annealing either with nascent transcripts or with homologous DNA sequences. We then review a third model that is based on our recent work on the role of the noncoding roX RNAs in the localisation of the MSL complex to sites on the X chromosome in Drosophila. Our results suggest that the MSL1 and MSL2 proteins bind to chromatin but it is the incorporation of the roX RNAs into the complex that somehow alters the binding specificity of the MSL1/MSL2 proteins to recognise sites on the X chromosome. ©2008 Landes Bioscience.