Exploring the complex world of RNA regulation

The discovery of catalytic RNAs in the early 1980s (T. Cech and S. Altman, Nobel Prize in Chemistry, 1989) entirely changed our views about the roles that RNA molecules are capable of playing. This breakthrough entailed a remarkable increase in knowledge about the folding of RNA molecules and their functional activities. Today, after the discovery of RNAi (RNA interference) (A. Fire and G. Mello, Nobel Prize in Medicine or Physiology, 2006), the role of novel ncRNAs (non-coding RNAs) in the regulation of gene expression and genome stability has become a major topic of interest. This issue (January 2008) begins a series of review articles, which will appear over several issues, providing insights into the integration of novel RNA-based regulatory networks in the cellular context in eukaryotes – animals and plants – as well as in prokaryotes, and into the many mechanisms of action that emphasize the versatility of RNA structure and function. Several exciting parallels become apparent when regulatory RNAs and their mechanisms are compared between eukaryotes and prokaryotes. Current knowledge suggests that RNA-based mechanisms are involved in all central processes of gene expression: from transcription, mRNA processing and transport, to translation and degradation. Several reviews highlight the direct role of RNAs in epigenetic gene silencing and transcriptional control (Barrandon et al.; Kim and Breaker; Royo and Cavaillé). Mammalian genomic imprinting is one of the epigenetic gene regulatory mechanisms