Book of Abstracts: Albany 2007
June 19-23 2007
RNA has emerged as a common factor in the regulation of genes in many systems. The concept of RNA as a single messenger carrying information from gene to the ribosome was significantly modified when processes such as alternative RNA splicing, alternative polyadenylation, and RNA editing were discovered. All of these processes modify, dependent on the cellular environment and type of cell, the nature of the transferred information from the DNA sequence to the ribosome. More recently, the discovery of processes such as RNA interference (RNAi) and the existence of hundreds of genes for non-coding RNAs, microRNAs, have dramatically changed our concept of the roles of RNA in cells. Here, short RNAs are regulating the expression of genes as transacting regulatory factors, a class of activities that had previously been reserved for protein factors. Over a quarter of all genes in vertebrates is probably regulated by microRNAs. Further, in many organisms, RNA directed processes mediate epigenetic gene regulation. The recently discovered class of short RNAs related to germ line tissue, piRNAs, might be involved in such regulation. Perhaps related to these examples of RNA mediated gene regulation are the recent descriptions of extensive nuclear transcription of apparently non-coding RNA in vertebrates. Alternations in regulation by microRNAs have been related to many disease processes such as cancer. With elucidation of the biochemistry of proteins important in RNAi and microRNA pathways, we can address questions concerning the evolutionary origin of these regulatory processes. They clearly predate the divergence of the plant and animal kingdoms, and structural analogs of many of these proteins can be found in bacteria. Further, it seems obvious that as the RNA world evolved into the DNA world, RNAs might have been retained as a major class of regulators.
Phillip A. Sharp
Center for Cancer Research and Department of Biology